You're definitely right about Rex's impact on the series. I guess I considered him minor because he didn't have a whole ton of screen time and then at the end of season 1, BOOM, dead. We really didn't learn much about him aside from the fact that he was a sex freak and that he was more often than not kinda jerkish. Guess we know where Andrew got that trait from, huh? I guess the same could be said for Martha and even Mary Alice since we barely got to know them either, so my observation about Rex being "minor" was kind of off-base.
So yeah, how bout this one: what if they had went through with their early draft idea for season 5 and had killed off Susan? How would THAT have affected the show -- one of the main 4 women dying -- especially the one that was arguably considered "the star" during season one?