@Gliblord:
Their senses were dulled? Where are you getting that? If anything they were better, what with regeneration and body morphing. Also they had plenty of emotions, so you can't say they were soulless automatons. There was basically no reason for them to want to be human. The homunculi in Mangahood recognized that and had Homunculus pride lol
It's been a long time since I watched this anime, but I remember that only Lust and probably Gluttony wanted to become human. The other didn't seem to care, Greed was completely satisfied even in the first Anime. I thought that most of them were actually trying to resolve a sort of existential crisis which was a consequence of their condition of monster with human memory.
Anyway, in Lust's case, it seems the transformation changed a lot of things in her psychology. She definitely had a different personality when she was human, the only explanation to this change is her transformation into a homonculus. She wasn't satisfied with her current form, I don't think they didn't have any emotions, but I'm sure they weren't as strong as what they were when she was human, she really felt too detached at some moments.
@Nobodyman:
Well, that's certainly worth killing 1000's of people for.
To keep on living as homunculi, they were forced to eat some red stones which were created with human body..
It seems I'm one of the only ones who enjoys the different version almost equally.