For the most part, I thoroughly agree. It's one of the reasons I like "closed canon", with definite endings followed by a world of possibility. (And I tend to dislike sequels that want to ruin my fun by telling me what "really" happened.)

I just find it funny how very clear my fanfic has always been on the subject of Dawn studying in Boston, or Buffy and Kennedy's drunken bitch session. Such trivial stuff, and yet I care deeply. :)