Does the Bible give any reason as to why its content is sometimes difficult to interpret?

A large part of it is that the Bible wasn't written for us. The various books were written by people thousands of years ago, for their own contemporaries. There are a few passages about preserving knowledge and laws for posterity, but in general it was written by, to and for people of ancient cultures. A lot of it is still 100% valid, since it deals with basic human nature, which doesn't change with time. But a lot of it deals with culture, which does change.

To give just one example, the Bible forbids the eating of blood in very specific and clear terms. The council in Acts 15 makes it clear that this prohibition still applies to Christians. But the Bible doesn't say anything about blood transfusions, for the very simple reason that the technology for it did not exist until recently. So what to do about them?

Some Christian churches are silent on the matter. Others, placing a high value on healing and the preservation and improvement of human life, actively support and help to organize blood drives. Others, though, interpret the prohibition against eating blood more broadly than what is literally written, stating that it is wrong to take blood that is not your own into your body, even through other means than eating/drinking, and therefore blood transfusions are a violation of the law.

Anywhere where the words of the Bible are not perfectly clear and completely applicable to some modern concept, people will find a need to interpret them. And with so much interpretation going on, some people try to squeeze in even more reinterpreting to get otherwise-clear passages to fit their agenda. (See for example the various "is X a sin?" questions, and count how many of them actually mean "can I get away with doing X even though it's generally/frequently considered to be a sin?")

Probably the biggest thing is, you cannot rightly understand before you have been born of God. This is different from claiming to be a "christian."

1Co 2:14 But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.

Joh 16:13 Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come.

If you are not willing to do God's will (give up sin and follow Christ), you cannot possibly know doctrine:

Joh 7:17 If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself.

So, basically sin is at the root of most, if not all, misinterpretations.

Yes, absolutely

First understand these premises, earthly wisdom and Godly wisdom.

James 3:14-15 (NIV)

14 But if you harbor bitter envy and selfish ambition in your hearts, do not boast about it or deny the truth. 15 Such “wisdom” does not come down from heaven but is earthly, unspiritual, demonic.

James 3:17 (NIV)

17 But the wisdom that comes from heaven is first of all pure; then peace-loving, considerate, submissive, full of mercy and good fruit, impartial and sincere.

This is the answer to your question

Isaiah was commissioned by God to go and rebuke a wicked people and deliver this curse to them.

Isaiah 6:9-10 NIV

9 He said, “Go and tell this people:

“‘Be ever hearing, but never understanding; be ever seeing, but never perceiving.’ 10 Make the heart of this people calloused;
make their ears dull and close their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts, and turn and be healed.”

Wicked people and the wisdom of this world

God has purposely shut off the understanding of His word to the common man. Because of that mans wickedness he will never know the truth about God. But if that man turns from his wickedness, repents, and has faith in Jesus Christ, then God will open the flood gates of wisdom so that you may understand His word.

Ephesians 4:18

They are darkened in their understanding and separated from the life of God because of the ignorance that is in them due to the hardening of their hearts.

Children of God

God promises a wealth of understanding when He gives you the Holy Spirit.

Ephesians 1:8

that he lavished on us. With all wisdom and understanding,

Isaiah 11:2

The Spirit of the LORD will rest on him— the Spirit of wisdom and of understanding, the Spirit of counsel and of might, the Spirit of the knowledge and fear of the LORD—

Colossians 1:9

... We continually ask God to fill you with the knowledge of his will through all the wisdom and understanding that the Spirit gives,