I was going to start a new thread, but I'll post here:
WHY VULCAN HAD TO DIE:
It's all about the symbolism for what's going on with the franchise, while not alienating die hard continuity fans by demanding that they forget that everything happened.
Vulcan is symbolic for Logic, the logic of the franchise that came before. Spock is symbolic for that franchise, which was a mix of human emotion and Trek-Logic.
The film is a revamping of the franchise, but the idea of Star Trek is such that one cannot simply do a non-canon movie for the fans WHILE AT THE SAME TIME as a writer it is near-impossible to do a good film with bundles of old plots and logic(s) hanging around clogging things up.
The villain (aka: that which moves the plot forward) goes back in time to before everything started and screws with time. More specifically, explodes the logic-planet IN, I suppose, a bid to get back at Spock (who was just trying to save their world). Spock survives, along with only 10 000 vulcans, rescuing as many of the culture-people as he can, and is going to try to save his people.
Our view: the movie: JJ Abrams takes the old franchise and blows it up, but goes back in time to do this. What does he use? The Logic, the Star Trek stuff that really matters, and gets rid of the rest; from 6 billion worries to 10000, from a story-teller's POV.
Spock symbolizes also the old franchise. He is all the stored memories of the old timelines, technologies, mathematics, whatever. He's an ARC, in a way. He's also the production's way of saying "we're keeping the past, and using it as a guide as we move forward". It's... well, it's a pledge during this revamp, that retconning will (hopefully) not be disrespectful.
I liked the movie, and this idea. What weirds me out is that none of the episodes I remember actually happened now. No trouble with Tribbles, no Amok time, no Picard, no Data... well, not yet. Eventually yes, but we'll see changes.
We might also see T'Pol make an appearance in the next film, or Tuvok, or some other interesting stuff. Heh, in this continuity have Klingons transformed into big-forehead guys like Worf?! heheheheh.