I think Reboot reopened a canon that people already knew really well but that had gotten closed up by so many iterations. Reboot set the clock back, like going back to Book 4 of Harry Potter or something. People have tons of canon to draw on, not just the movie, but it's no longer binding - one big AU.

Not saying I think it will last, but I think that's one reason it's so generative.

Merlin was a very short season, with a big gap between UK and US airing. This is apparently to be the wave of the future - wonder how that will work.