You can immediately attack another player, and the window where he can be attacked/offer a bribe should be fairly short, at most you lose a few minutes (Which you can spend doing other things anyway). And you get essentially free resources.
Another thing I keep telling people, you're going to have more than enough resources to field several max battalion-cap armies as the game is right now, I doubt people are going to avoid fighting as if it's the plague. You only have to repair your buildings and start raising another army while bringing one of your spare armies back to your city, it's not the end of the world. You don't get set back all that much.
If for some bizarre reason nobody is willing to fight we'll just keep increasing the price for it/make it so you can only bribe so many times in a certain period or something along those lines. We're not going to just let the game devolve into Sim City. I'm pretty confident you're all worrying over nothing however, I find it hard to believe that many people are going to actively avoid fighting, especially in defense of all things where they have a pretty decent advantage.