score:17
I think you're right to question the importance of rebirth; the Buddha himself didn't seem to dwell on the concept, though remembering one's past lives does have obvious practical benefits - lots more experience to draw upon :)
Bhikkhu Bodhi wrote a couple of things about the subject you might find interesting:
As he says in the first link,
If we suspend our own predilections for the moment and instead go directly to our sources, we come upon the indisputable fact that the Buddha himself taught rebirth and taught it as a basic tenet of his teaching. Viewed in their totality, the Buddha's discourses show us that far from being a mere concession to the outlook prevalent in his time or an Asiatic cultural contrivance, the doctrine of rebirth has tremendous implications for the entire course of Dhamma practice, affecting both the aim with which the practice is taken up and the motivation with which it is followed through to completion.
I've talked about the subject before myself, and the conclusion I make is that it's not that Buddhists believe in rebirth, it's that we don't believe in death - the latter being merely a concept referring to the change from one set of experiences to another. True death only occurs either at every moment or at the experience of nibbana.
In any case, as useful as rebirth may be in reminding us of what's really at stake in our dhamma practice, far more useful is an understanding of the present moment, something that really has little to do with past or future lives.
Upvote:3
If I understand your question correctly, maybe the following notes may be of concern:
Buddhism as a philosophical current or religion evolved out of an ascetic movement that was very much concerned with personal salvation, the so-called śramaṇa-movement. Apart from buddhism, the relics of this movement is the Jaina religion and historically a religion/philosophy called Ājīvika, which died out only about a thousand years ago. But also the mainstream orthodox Hindu schools of philosophy owe very much to this movement. Stories of wandering ascetics questioning the Buddha about his doctrine, arguing with him or stories of the Buddha, who at the sight of ascetics warns or teaches to his followers abound.
In this movement, rebirth was more or less totally taken for granted (some exceptions, the materialists for example, exist), it was common sense. That is why in Buddhism you can find the same attitude. People critized and attacked the Buddha on grounds of his specific doctrines (most notably rebirth without soul - anattā/anātman) but they hardly ever or never doubt rebirth as a concept. Since the Buddhist scriptures very much reflect the philosophical discussions of the time of the Buddha (and after), there was just no need, to give reasons, explanations, proof for rebirth.
In the Samaññaphalasutta a lot of rival views are examined by the Buddha, you might check there, if the materialists are quoted denying rebirth and what the answer of the Buddha was and whether he actually defended the concept of rebirth in any way.
This can be summed up by quoting from Yuttadhammo's answer:
it's not that Buddhists believe in rebirth, it's that we don't believe in death
Concerning the unanswered questions, I guess the one in concern would be, whether the tathāgata lives on after death. This, though refers to an enlightened being, someone who has attained nirvāṇa and so has left the cycle of rebirth. So, strictly speaking, it is not a question about rebirth. And by the way, as far as I understand the scriptures, the Buddha denied to answer these questions or simply remained silent, when asked, because the question cannot be answered correctly in words. Other questions were refused to answer, because the Buddha did not intend metaphysics or anything that was not considered conducive to salvation, liberation.
Now, to conclude, the notion of rebirth is totally central to Buddhism, since Buddhism essentially is a response to the perceived fact of rebirth, that has, as has all life, the characteristic of being laden with (within the bounds of the samsaric cycle) unescapable sorrow. Essentially, the Buddha didn't teach a happier mode of life, but that all life is bound to be miserable and the way out is the way out of life (which in this case does not mean death, but nirvāṇa).
Upvote:4
The Buddha said never to accept something just because it was said, but to seek an answer to these questions yourself.
If you don't know for sure either way. There is no need to believe anything either way.
Upvote:6
If you are into Vipassana meditation, you must have noticed that experiences rise and cease one after the other. When one experience ceases, another will arise. It doesn't stop! Likewise, death is also another experience in reality. It doesn't prevent the next experience from arising as long as the causes for arising haven't been eliminated. I recommend you to go through the "rebirth/reincarnation" Q&A section at http://video.sirimangalo.org.
Some questions are unanswered in Buddhism for several reasons:
"Becoming one with the world" can be misleading as it can imply the Hindu concept of the universal soul. The Buddhist teaching is that you are just another process of causes and effects which are impermanent, subjected to suffering and devoid of any self or inherent value. Just like everything else in the universe.