lol, why not? Also you have to remember that their was a MLP show back in the 80's and many people who remember that show watch the new one. It's a little bit why so many watch Family Guy is because of all the references to 80's culture the show makes :)
Also MLP isn't exactly a child's show. Sure it's ok for children but it's one of those shows that make children and adult references about things albeit alluded to only.
I personally love animation of all kinds. I respect the career of voice acting and I love feeling like a kid again :)