I think it was aimed at making the OS look less threatening and complicated to a new user. Then again, people did complain about it being a "Fisher-Price UI", so maybe this overwhelmingly positive perception is a result of people spending so much time with the OS and getting used to the way things were.
I do recall the Fisher-Price complaints. As I recall it mostly came from the Linux (or Linux-inclined) crowd. I never really understood the complaints, though it was common enough that I must have just been missing something. But really, I don't get whats wrong with a functional UI that's also friendly and inviting.
Just today I was thinking about XP and the phrase "Fisher-Price" came to mind. I liked XP's UI, even as whimsical and toy-like (and easy to make fun of) as it was. I'd prefer if computers and OSes retained the whimsy and character of that late-90's-early-2000's era of Win XP and the colourful iMacs, etc.
