I agree with the rest: a weekly show on that sort of situation would get old fast simply because of the dark subject matter and because of the stereotypical plot lines and hooks we'd get week after week.

As for the spin-off, I frankly don't understand why people are so dead-set against it. Character sketches are just that: tiny sketches. Take your favorite shows and try to put the entire personality of all the characters into one/two sentences. A lot of it is gonna sound stupid, overplayed, or outright silly. (Try putting Reid or Prentiss through that treatment: I guarantee you, it'll sound bad, no matter how you do it.) I'm giving it chance and refuse to make a broad judgment based on two paragraphs and characters sketches -- I'll wait for the episodes to air. :)