So because we're stuck with arbitrary lines no matter what, we should go with a dozen of the instead of just the one that divides the two distinct leagues that have distinct rules?
You really seem to be hung up on "winning a division", which is and of itself is... not that impressive. Especially when you have 6 divisions with as few as 4 teams (weak ones, at that) in them, and three of the best teams in baseball crammed into a single division. Why not make 8 divisions and have 8 division winners? haha. That'd be much better than having 1 division per league and all those pesky, undeserving wildcards