Well, I suspect that part of the reason why Smallville has lasted so long is because of the relatively low ratings standards of the WB/CW. It certainly has never had to maintain the kind of major network presence of The Flash, The Tick, Lois & Clark, or the Adam West Batman series. And didn't The Adventures of Superman only end when it did because George Reeves committed suicide?
The other reason is also because all that most mundanes want out of heroes is people that are fucked up like them. God forbid if a producer decided to do the original version of teenage Clark Kent as seen in
Superman: The Movie, Superman: The Animated Series, or as seen in the flashback sequence of the teenage Clark Kent in
Superman Returns-it would be considered 'unrealistic' and 'corny' because Clark Kent isn't a whiny emo-boy (this despite the fact that
John Haymes Newton and Gerrard Christopher were able to play the original Clark for four seasons on
Superboy, and also despite the fact that this version was quite popular!) It's why all of the characters on
BSG are the way they are as opposed to the original versions of their characters-everybody these days want a little bit more 'oomph' in their personalities. The problem with this is, sometimes it works, and sometimes it doesn't. And it really hasn't worked with the
Smallville version of Clark Kent, either. But, that's want people, particularly the viewers of the WB/CW, want to see. So, that's what we all get (we also can't get people in costume on TV for the same reason, despite seeing people in costume on the big screen!

)
As it is, I'll never waste my time watching
Heroes or
Smallville-
the former I've already come across in comic book form as
Psi-Force, the latter as
The Tomorrow People. There's no real reason for me to watch either show, unless both get remade as per the topic the OP posted.