The current version of My Little Pony does have family appeal - lots of it, in fact. The appeal of MLP right now can be compared to the appeal of the PowerPuff Girls - girly yes, but not too girly, with just enough humor, developed characters, and occasional action to appeal to many kinds of people, including boys.
As for Dora the Explorer, yeah okay, I'm not going to defend that. Dora's definitely little kid's stuff. (and when it comes to Nick Jr. shows, the likes of Blue's Clues and Eureeka's Castle were much, much more likeable.) But I think it could still make an interesting attraction if executed properly, something I'm pretty sure Universal can do.
Personally, I agree with many people here in that the Kidzone should be made into a Nickelodeon land. Have attractions for SpongeBob, Fairly OddParents, TMNT, Jimmy Neutron and The Last Airbender, but also have a Rugrats attraction and numerous references to old-school Nick to appeal to the older folk, that way everyone can have their cake and eat it too. Probably won't happen, but it's a nice thing to dream about.