Concussive force actually obeying physics and not stopping dead at your armor would be a very firm reminder of one’s mortality, even if it’s just a little at a time or one single hit point guaranteed beyond a given threshold.
I put up a seperate thread about it on the Drawing Board. I have a feeling that keeping a player from truly becoming invincible will make certain threats still feel like a threat at any point in the game, because seriously, you can’t just step on a landmine and have it blow up and have absolutely no effect on the person. It just doesn’t work like that. Same with being put through a wall by a Hulk. The force alone from the punch would do some hurt, regardless of how dense your armor is, not to mention the impact with the wall enough to put you through it.
Certain things should always just be dangerous. No matter how mutated or bionic-infested one becomes, the player can only ever be human. There is no way around that in real life and there shouldn’t be in game, because it gets extremely boring very quickly. People still need to be able to get hurt or there’s no point in playing.