The point is to continue the new story of the new crew of the new Starship Enterprise.  I kinda figured that was obvious.  Just because the new movie continues from a new timeline doesn't mean the previous 40 years of Star Trek is useless.  TOS, TNG, DS9, VOY, and ENT and the movies aren't going to go away just because a new movie comes along.  Besides which, a new movie also paves way for a new series, possibly in the Lost Era or post-Nemesis era.  More success with JJ's timeline means more Trek.