Re: So why doesn't Spock save Vulcan?
It's akin to the crap they pulled at the end of DS9 - Having the Defiant destroyed was a hugely dramatic moment...and then the next episode introduces the new Defiant, an identical ship to the first solely so they could re-use all the stock footage of a battle from a previous episode for the finale, and the characters didn't even bat an eye about the loss of the old ship. Intensely dramatic moment gone in one week. Fail.
Imagine if they had ever pulled something like that with the original Enterprise.
Whatever happens on earth, that up there, that's the endgame.