he started the war to capture all tailed beasts.
He needs the Juubi to get the moons eye plan fullfilled to create the perfect world for himself and Rin.
(>>>Even if he cannot revive Rin he is thinkin by this he will create a world which Rin would like).
Thats my understanding. :shrug:
On the other way round I must ask:
Why is Tobi/Obito trying to get the Juubi, if it has nothing to do with Rin?