So far, Pixar has produced a total of one full-length feature sequel, and it did even better than its lofty predecessor. So I think there's something to be said for sequels that are done right (that's the important part).
I don't believe there's anything inherently wrong with the idea of a sequel. Sure, the characters are already established, but that just means that the filmmaker gets to dig right into the story rather than spending time with introductions. Nothing wrong with that. Should every Mickey cartoon that's come out since Plane Crazy be considered somewhat inferior simply because the character is already established? (Not that anyone implied that, I'm simply commenting on the notion that sequels are regarded as inferior product)
I think they have to be judged on a case-by-case basis, not to mention the "desire-to-see-it" factor. Do I want to know what happens after "Happily Ever After" in Cinderella 2, 3, or 4? Nope. But would I like to see John Lasseter make Toy Story 3? You bet. As long as it's a great story all the essential elements are still there ('cept for Jim Varney, of course).
Now, having said all that, would I wanna see Pixar make sequels out of all their movies? Nuh-uh. There's gotta be balance. When Disney puts out more sequels per year than feature films, there's a clear problem.
