Originally Posted by DigificWriter
Creating a new timeline doesn't mean erasing everything and starting over; go look at what was done with the 2009 Mortal Kombat game. As far as I know, the only significant thing that the game changed with its alternate timeline is that the younger Sub-Zero was automated instead of Smoke.
That's exactly the point. OP isn't talking about erasing everything and starting over. He's talking about taking everything that happened in 1,2,3 and Origins. And using it to change the entire course of X-history in DoFP.
So the memories of Wolverine and McAvoy Xavier are what keep those films alive (not to mention those films themselves because you can always go back and watch them) and the new cast gets to go on their own adventures without being tied down by the events and actions of the original cast. Including allowing Cyclops to live on and getting Magneto into the action a lot more regularly. Both things I really want to see.