Is it bad to be too childish?

I'm 14 years old and I find myself loving every single thing I still love when I was a child. I still collect Barbie dolls, except I don't open them, since I realize how valuable they are. I watch little kid movies from the 80s and 90s, because I love the thought that anything is absolutely possible. That there are knight in shining armor. That there are dreams to fight for. My parents thing I should learn to be more serious. Every time I do something wrong, they say "I'm 14 and I should know better." My actual favorite movies, (besides Titanic, Love Story, and a whole lot of Mel Brooks movies) are usually for kids. I collect all the Barbie movies and all of Don Bluth's movies, such as Xanadu, Thumbelina, and Anastasia. And everywhere I go, I see little children who are five years old. Most of these little children are some of my best friends. I have more fun with them, more than with friends my age. They just have more imagination. And I love playing little kid games. Now what I would like to know is this, is it good to be childish. Or is it bad. I don't think I ever want to grow up.