Think of pre-Abrams Star Trek as a Christmas tree. For 40 years ornaments have been added.... and added... and added... until it got to the point where it was about to tip over from it's own weight.
Now we have a fresh, strong new tree to decorate.
Now there is no need to say, "You can't do that because it contradicts what was said thirteen minutes and twenty seconds into the 18th episode of the 4th season of The Next Generation."
We now have all the characters that we know and love... but they are not quite the same. With the weight if history lifted from them there is now enough space (pun intended), for them to perhaps grow in an entire new way.
Trekkers of the world.... REJOICE!!! In a flash there are now a thousand and one truly NEW Star Trek stories to be told!!!