I like what the original poster wrote about combat realism, I could concur with a lot. The problem is that realism in a game is difficult to achieve, firstly because of resource restrictions, secondly because of game fun (troop tress for example, which are really nonsense, but fun), thirdly because of multiplayer. For me multiplayer is the direct contradiction to "reality fun" (or fun at all), as it needs balance, and reality is not balanced.
Usually gameplay reasons win. For example in M+B Warband I preferred to play 1268 as my mod. I was really annoyed how vulnerable you still were in top tier armor and greatly increased the damage resistance. On the other hand I let the top tier armored cavalry knights remain in my favorite faction (Irish) although that was not historically correct at all, otherwise my chances to deal with better equipped nations would have been even worse. So game fun/balance won against realism.
Soldiers in M+B by and large use too much armor, or better said, there are too many soldiers with good armor, by a huge number. The troop trees urge to get better and better troops, and all wear the same amount of armor. If the weapons would show the (often bad) effects they had against armor in reality, gameplay with certain units would be not fun for many players. I would like a more realistic behavior, but that would mean also a large random factor in combat (because your impenetrable plate armor was of little use if hit through the open visor, or a badly made or uncovered area, and such things).