Some parents prefer their younger kids to play with only wholesome (as defined by the parent) toys that don't delve in themes considered too mature for them.
I wasn't allowed to have Jem dolls because their had colored hair. I grew up with an obsession over forbidden blue hair. I'm serious, telling a kid they can't have something makes their young minds ache for it all the more. I colored my red and blue last year. I told my Mom, jokingly of course, that she should have let me have a Jem doll and I could have lived vicariously through my dolls. I did "borrow" blue markers and color Barbie's hair but it didn't turn out to be a good job :-p