my first thought was more fights in the stands and parking lots.....as there would be many more fans from the visiting teams in attendance ( would need to double security).
my second thought was more attendance improves our chances of keeping the team in buffalo (best reason for it).
my third thought is that although you can make an arguement it's better for buffalo, it would be next to impossible to make it better for every other team, the elimination of current rivalries, the perceived competitive disadvantage to be put with a team(s) that is currently strong, more travel for some, therefore i doubt this goes very far (thinking of the recent NHL realignment talks). although your suggestion only involves switching the bills and ravens.....if i'm a ravens fan, i dont like the (ne, nyj, mia) alignment.
having said all that, i think total league wide realignment is a good idea, would benefit more teams than it would hurt and should be looked into. however, if after that plan, a team relocated, say jax to los angeles, it would mess things up again.