Sorry to drag this back to "Tangled" but I was thinking about it again recently, having just re-watched "Aladdin" and "Mulan" (and a couple of other musicals) and I think what I found difficult about it was that the songs don't progress the story at all.
If you take "Be a Man" as an example, SO MUCH happens during that song. It takes you from point A to point B during the song, in a rousing and exciting way. None of the songs in "Tangled" seem to do that. Even your basic I Want style song should take you from not knowing the character to knowing who they are, what their life is like, and what they want / need to change. In "Tangled", the I Want number is about how she wants to get out of her tower. That's kind of a no-brainer, isn't it? We all recognise her as Rapunzel... I feel like all of the songs are weirdly static in "Tangled" and they don't move the story along.
I'm just flinging ideas around here but it's something I've been mulling over. Any further thoughts?