From a Buddhist point of view, what are the benefits of supernormal powers?

One siddhi worth mentioning is the one called "anima," the ability to see atoms. Almost a century ago, two clairvoyants, Annie Besant and Charles Leadbeater, used this ability to examine all the elements of the periodic table known at the time. More recently, a physicists named Stephen Phillips found a mathematical relationship between their observations and our modern knowledge of the elements. Someday, I suspect, people will be developing this siddhi in order to provide new information about atoms for modern physicists. I suspect that the same siddhi can also be used to observe the physical form of citta. But that is another story.

The greatest danger by far is always going to be emotional attachment to the attained skill, or to attainment itself. Attachment is death, the only real death. Our connection to any version of who we think we are limits our potential for movement and growth and any desire limits us similarly. Power feeds the mind's yearning to solve problems, and that yearning manifests even larger problems, so despite our good intentions, we are working with the discipline of infants when provided with new tools of potentials previously seen as magical.

Seems like you are referring to iddhi powers which are extremely important in achieving arahantship.

Developing the four bases of iddhi seems to refer to developing concentration founded on desire, persistence, intent, and discrimination (SN 51.20).

It says in SN 51.7:

“Monks, all the monks in the past … future … present who realize the undefiled freedom of heart and freedom by wisdom in this very life, and who live having realized it with their own insight due to the ending of defilements, do so by developing and cultivating the four bases of iddhi power." (SN 51.7)

This means it's impossible to achieve arahantship or the ending of mental fermentations without developing a certain degree of iddhi.

It's not the superhuman powers themselves that are important but the well-developed concentration ability required to achieve those powers which is important which is required for achieving arahantship.

Now I understand why my own personal progress in achieving arahantship is halted I'm only a little skilled in iddhi development though I've achieved higher states and have experienced some effects of iddhi development here and now.

Originally desire and enthusiasm was viewed as important and beneficial in Buddhism for achieving arahantship even though now the popular media portrays the opposite (I think this is in part because of the disappearance of arahants).

Right Effort is part of the Noble Eightfold Path:

"And what, bhikkhus, is right effort? Here, bhikkhus, a bhikkhu generates desire for the nonarising of unarisen evil unwholesome states; he makes an effort, arouses energy, applies his mind, and strives. " (SN 45.8)

Sariputta took a week longer than Moggallana to achieve arahantship perhaps because Moggallana was much more skilled in iddhi development than Sariputta.

With developed iddhi powers one can do nearly anything.

Moggallana boasts:

"Sāriputta, the monk who has crossed over, may be supreme in respect of his wisdom, ethics, and peace.

But in a moment I can create the likenesses of ten million times 100,000 people! I’m skilled in transformations; I’m a master of psychic powers." (Thag 20.1)

Based on the suttas looks like it's necessary to develop a certain level of concentration to achieve arahantship.

In general things can be beneficial if it leads towards arahantship, but maleficial if it leads away from arahantship.

Iddhi development is necessary for achieving arahantship, easing doubts, perceiving the truth, and especially useful if one decides to become a teacher.

What type of teacher would The Buddha have been if he hadn't developed supernormal powers to a very high degree? It would've been extremely difficult to teach and know certain things.

"It is because he has developed and cultivated these four bases of iddhi power that the Realized One is called ‘the perfected one, the fully awakened Buddha’" (SN 51.8)

Remember The Buddha used his power to avoid the serial killer Angulimala, who He converted into a monk who eventually achieved arahantship and also used it constantly for teaching (like looking into someone's past existences to see what teachings would trigger unconscious memories that lead towards arahantship).

Iddhi development was encouraged for monks but displaying iddhi powers became viewed as a negative thing after the arahant Pindola Bharadwaja started flying in public to take down a bowl. Now in modern times it seems because of frauds, imposters, non-arahants, the faithless, and other incapable people iddhi powers are viewed as even more negatively even though a very positive thing for achieving arahantship.

Iddhi development may be viewed as more negatively now probably because of the disappearance of real arahants existing in the world but it is still extremely important for those desiring to achieve arahantship.

"Monks, whoever has missed out on the four bases of iddhi power has missed out on the noble path to the complete ending of suffering." (SN 51.2)

This is a Buddhanet-quote from a section called "The Buddha's Attitude to Miracles":

"The only miracles that should be performed are these: when you see a man full of passion, craving and greed and you teach him to free himself from passion, craving and greed; when you see that a man is a slave to hatred and anger and you use your powers to help him control his hatred and anger; when you come across a man who is ignorant and who cannot see the true nature of the world (everything in this world is impermanent, sorrowful and egoless) and you use your powers to help him overcome his ignorance. These are worthy "miracles" you can perform.

This advice to Kevaddha was also extended to the Vinaya rules that forbid monks from performing miracles to impress people and gain converts, without helping them to be enlightened. This was clear in the case of Pindola.

Arahant Pindola Bharadwaja was famous for miraculous psychic powers. A rich man, wanting this monk to prove his psychic powers, placed a beautiful bowl at the top of a high place and challenged any holy man to get the bowl down. If he could do it, he could keep the bowl.

Pindola Bharadwaja flew up and took the bowl down easily. This was also done to prove to the rich man that there are saints in the world, a fact that the rich man did not believe. When the Buddha came to know about this incident, he called Pindola Bharadwaja to bring his bowl. He broke the bowl into pieces in front of a large gathering of monks, saying, "I am displeased about the demonstration of your psychic powers. You must never show off your powers just to impress simple ignorant people."

The first paragraph illustrates how these powers should be used, i.e. to help other beings become free from the defilements so that they can develop their faculties. So i think that must be the some of the benefits. Being able to help other beings thereby doing wholesome actions creating wholesome effects to ripen in this life or future lives.

What we also see from this text is that the Buddha placed great emphaziz on people, especially monks not abusing these powers and thereby giving the Sangha and more broadly speaking Buddhism a negative reputation.

When that is said i think its of great importance that such powers should be in the hands of clear-seeing, highly developed beings and not beings who still have a gross level of the root defilements in them. If that is the case the powers might be abused.

In addition to what @Ryan wrote about the Buddha helping people with powers, it can also guide the aspirant.

One may use powers to read other people's minds for example, to understand the nature of anicca. Since one's own thoughts may appear too personal and arising with just cause, seeing the thoughts of others change from time to time, may drive home the point that it is affected by causes and conditions, and is compounded.

Even though every mature teacher recommends not getting side tracked by powers, the lure of powers is like candy to children for some. Experiencing the powers can convince such people that they are not worth lusting after. Of course, they can also lose their head, and behave like Devadatta.

The Buddha himself when he attained enlightenment analysed his past lives with great interest, and learned without a shred of doubt the futility of eons of lives spent lost in pleasures, not searching for the truth.

An Indian yogi came to Japan and demonstrated his ability to levitate and other supernatural powers. The people who witnessed these miracles went to the Zen master living nearby (Bankei) and asked "See what this yogi can do? What miracles can you perform?"

The Zen master responded "When I'm hungry I eat, when I'm tired I sleep."

Just from inferring from the texts, you can see how the Buddhas ability to read people's minds allowed him to teach them exactly what they needed to hear. So such an ability would allow someone greater ability to teach people. I also seem to remember in the dhammapada, accounts of the Buddha using his omniscience, seeing understanding arising in monks minds, to telepathically communicate with the monks who were practicing far away in a forest to give them assurance on their path. So as far as I can tell, these powers are to be used to help others on their paths.