Does the game punish you for playing defensively?

I feel that one of the biggest glitches in the way the game is balanced is that you can build the best defensive structure imaginable, which then gets torn to pieces by a bunch of post imp champions with anarchy in under a minute. I'm debating writing a mod/patch to fix this but curious to hear any thoughts.

Given the time period that the game is based in, you should be able to build heavy fortifications and hold out for longer than a few minutes against an encroaching army.