I'm torn on the issue. On one hand, i dislike the addition of Stitch, and even the infusion of Pixar characters like "Nemo & Friends", although i own and love Lilo & Stitch and all the Pixar movies. But on the other hand, how long do you need to wait before you create an attraction based on a character? And if they never created new characters for the parks, then we'd never have Figment and Dreamfinder, the Country Bears, the Tiki Birds, or the Hitchhiking Ghosts. (then there's the whole Jack Sparrow addition to Pirates of the Caribbean, not sure which category that falls under)
I think it would be kind of cool if Disney Animation and Imagineering worked with the Mexico tourism board to create a new character to act as a guide on a refurbed attraction. That's the kind of thing that USED to happen back in Walt's day. The original 9 old men were both animators and imagineers, not to mention tinkerers and geniuses. I'd like to see the animation and imagineering groups cross over a little more again, and create really interesting experiences. (i'm really hoping that John Lasseter thinks this way too)