Criticism in the movie
Okay so anyone who watched the movie realizes every single moment of it is overflowing with metaphoric criticism of society. Especially the animations (most beautiful segments of the movie IMO).
So what do you think the movie criticizes more than all? In my opinion it mostly criticizes conservatism which oppresses people's freedom of expression and forces them to obey the accepted norms of society. But it also criticizes utopianism, an attempt to correct all the faults of society and create a perfect one, without considering the imperfect human nature.
Other criticisms are about war, materialism and hedonism.