Was a reboot necessary?
What Trek needed was to be revitalized. A reboot was not the only way to do it. However, it was the path of least resistance (I don't mean that as a fault, it's just the facts), and it most certainly worked.
Now, was the way they did it good? I'd say no - there was absolutely no need for an origin story. There was no real need for any time travel schenanagans. There was no need to destroy Vulcan. There was no real need to bother with canon, other than have the characters everyone knows - it could just be a self-contained story!
I do think it pretty much needed to be a Kirk-Spock Trek, though. The public knows Kirk, Spock, and the Enterprise. They know TNG better, but the cast is old, and TNG is old. No one outside of the fans knows anything about Voyager or Enterprise, and it was far too late to do anything with DS9 (not that anyone knows about that show, either). But Kirk, Spock, and the Enterprise are cultural icons. Do it right, and it's almost a license to print money, especially by 2009 when geeky retro things were OK to like.
I also think it needed to be an action film. Did it need to be brainless like Trek '09 was? No, but that obviously didn't hurt any. Plus, it's not like TOS isn't familiar with brainlessness.