The reboot makes sense to me. Alternate universe means that the current franchise can still exist and spawn stories and/or that the timeline can be righted. If it's true that Old Spock stays in NuTrek universe, then this forms the bridge between the two universes that makes us give a damn in the first place. Just suppose there hadn't been a reboot/alternate universe... OK, we KNOW everything is going to work out predictably, and that everyone is going to be okay... so then why should we even GIVE A DAMN? But it's been established that anything can happen. Nuking Vulcan creates more story potential, IMO. And no, I haven't seen the movie.
That's a pretty callous comment-- everyone is NOT going to be okay. And some of us do give a damn about killing an entire planet that has played a very important part in the mythos.