Some thoughts on your thoughts:

David Lean is one of my favourite film directors. A Passage to India is not one of his best (my top choices: Lawrence of Arabia, The Bridge on the River Kwai, Brief Encounter, and Great Expectations), but I do think it's a very good film regardless, given the impossibly high standards set by his other work. I can't help but feel angry at how Lean took the silly criticism of his films personally, which is why there was such a large gap between Ryan's Daughter and A Passage to India. I feel angry at both the critics (who were wrong) and Lean (who shouldn't have been so thin-skinned). Ryan's Daughter is a bit long, but it is clearly a masterpiece. I can't believe the critics were harsh about Doctor Zhivago either. As Martin Scorsese would say, what a picture!

I'm a big fan of the other Forman films you mention too.

In terms of your pop music analogy re: Mozart's upbringing, I can't help but think of the Jackson Five and Michael Jackson as an interesting point of comparison.