There's still plenty of stuff to talk about that didn't come up in the first one, stuff that's now taken on new relevance. The biggest "what might have been" is the original plan, circa 1980, to just keep going with the series and make episodes 7, 8, 9 and so on. Instead, GL decided to just condense all that into a nice, safe ending for the trilogy where Han Solo lives and Leia is Luke's sister. What we could've gotten is a nice series of six films with the same cast, each from a different director, and then an Episode I in the mid-to-late 90's (again, different director). The original 1977 movie should've remained the only Lucas-directed Star Wars movie.

I think a lot of what people don't like about the prequels goes all the way back to the problems with RotJ. My biggest problem with the PT is its execution, namely that it was directed and scripted by Lucas. But the overall story of the PT was always GL's to tell, just as it had been with the OT. In that sense, I don't see much point in rebooting the prequels.