Regarding sequels, I have to agree with Mr. Croshaw.
I absolutely hate it when sequel developers claim that they're trying "pay respect" to an old franchise. As an artist, I could say that I'm "paying respect" to Leonardo da Vinci by tracing over the Mona Lisa and slapping it on a canvas, but in the end, all I'll have done is exploited a famous piece of artwork and pissed off every Italian in heaven.
However, I do think that a good sequel is possible in the hands of a die hard fan. Sure, most fans would probably fill the sequel with all the textures, running gags, and characters that made the original great, but in order to keep my faith in humanity, I have to believe that some fans would be willing to try and make the game their own.
If we consider games to be an art form, then we have to consider them a form of self-expression first. Returning my previous metaphor, several artists have used the Mona Lisa in their work (ex: Dada), but what separated their work from mere plagiarism was the fact that they took it and made it a part of themselves. That said, I truly believe that the best sequels are those that are completely detached from the original. I applaud any developer that takes the giant risk of taking an old franchise, and instead of giving it a new look, gives it a new personality altogether.