Because it slows down the development or Versus significantly.
But in exchange, we have more Lightning...
Also, should have probably mention this in my other post
But then there is also the fact that some might not even like Lightning that much, so a game with just her might not even be appealing to them. Then there are the ones who don't hate FFXIII, but got into it for other characters/story/world/battle system. So it might not even appeal to them now and they'd just rather have something different at this point
This doesn't really reflect my opinion fyi. Just saying
I'll eat a sock if VersusXIII is actually a mind blowing game. -PainsPerception
Actually, Lightning is what makes a lot of people like look forward to the game even more as she has a fair ammount of fans~ Not to mention, this isn't going to slow down the actual development of Versus at all.
It may, however, give them more time to develop the game more fully and completely, as they won't want to release Versus right after LR. This would be a good thing. They also make test out some of the mechanics in Versus in LR and see how it goes. ^ w ~