I admit I'm an adult and I love Disney. Only been 1-2 times in my adult life, though. It's a combination of a few things:
1) A lot of nostalgia from the few times I went there as a kid
2) Disney is amazing at building little worlds... the architecture and detail throught the park is fascinating (like how they can make an otherwise boring food stand look like dwarves live in it).
And they never break character, no matter who they are. I wear a fedora, and we went to the 50's cafe. I had a black waitress that was probably 30 years older than me, who kept calling me "massa". I seriously looked at her the first time she did that and said, "wow, you people never break character do you?" She didn't even change her expression. She was a
waitress, not an actress playing any known character.
And a lot of the real resturants in the parks are just plain cool, whether or not you have kids. Remember Cinderella's castle that is in every advertisment? There is a 6+ month advance reservation resturant inside there, where all the servers are characters from the movie. And they don't do this half way, this looks
real up close, even when you know it can't be so. However, that turned out to be $150 per plate, so I never did it again; but
damn, was it an entertaining brunch.