The brilliant thing about the new timeline is that STAR TREK'S future is not set in stone. They can do whatever they want with these new versions of the characters.
Which they could have done with a straight reboot. Or am I wrong in this assumption?
Sure, but the time-travel gimmick makes it more Star Trekky and let them include some nostalgic scenes with Leonard Nimoy. And it may have helped ease some of us old-time Trekkies into the new version.
Fundamentally, the movie is a reboot. The alternative universe business was just a clever bonus.
I didn't need to be eased into a re-boot though. To me the only thing this movie needed was an engaging story. Which it didn't have. Which is a shame because they wasted some very talented actors.
Star Trek had went to the time travel well about seventeen times too often prior to this film and Leonard Nimoy really felt out of place to me.