The issues I have with crush through are:
1) It punishes manual blockers as well. It in effect removes your RMB from the game. If you don't see how removing someone's RMB is stupid then I dunno what to say.
2) It crushes through chamber blocks. If I chamber your overhead, I worked harder than you did and deserve my parry + hit. Not to just get crushed anyways. It's dumb.
3) It doesn't take my shield skill into account. I have 7 shield skill. Not 2, not 3 like guys that just put enough in there to pick one up as they advance with their 2her, but a significant investment into the skill. Coming up against a crush through user is like someone saying "Yeah, those 3 extra stat points you could have had, they were wasted."