I'm not sure I see the problem.
If we were talking about a boardgame or minis game, where your opponent (the other player) always tries to maximize the moves of his forces, then specific rules for freezing certain units makes sense.
But in a roleplaying game, I expect the GM to play the opponents, whether creatures or npc's, appropriately. Most of the time this seems to end up with the various fighter types hacking on each other, but a smart opponent will sometimes do something else, just as the player characters would. And various creatures will have their own motivations that will guide their actions. All of that lends verisimilitude or whatever to the game.
And again this comes back to what you want out of a system.
There is no internal consistency in a system where there is no penalty for walking around the fighter, but it is assumed that monsters don't do it anyway. Internally inconsistent systems are generally bad. You're saying 'well, there's no particular reason that everyone in your world doesn't do this, but... don't let them do it anyway.'
Now in the real world, why did warriors in combat not walk around each other and go cut up the archers? Well, if they just walked around another guy with a sword and went after an archer, they guy with the sword they were walking around would probably cut them up real good. He'd probably also try to protect the archers, keep the enemy from reaching them, make it harder to wound them.
The mark system and defensive auras were two good solutions to make a mechanical representation of what happens when you try to ignore the big guy with the sword.