My brother recently decided to undertake a mission to re-watch every single episode of Dallas ever screened and every time I phoned him up, he'd just want to talk about some random episode I couldn't remember.
I think they have a comfortable nostalgia about them, and they should leave a good thing alone.
Good point about Larry Hagman too. He was perfect in the original series because he was convincing as a dynamic alpha male, not sure that would be the case these days.