...but is is the sort of simplified "I only have to protect these guys and not look out to protect the rest of the party, because the AI only attacks those I want it to" gameplay that provides little tactical challenge (and seems bloody difficult to justify unless the opposition is described as insane), which is why you'll not find it in traditional pen-and-paper or computer roleplaying games.
I couldn't disagree more. The concept of tanking doesn't suggest the AI will ignore everyone but the tank. The tank should be somewhat capable of drawing attention, however, and that just is not true in this game. The AI will hang back and attack the ranged characters from afar. Drop smokescreen - well, most of the time it bugs out and they continue to fire regardless. When smokescreen does work, the AI just walks through it until it can continue attacking the ranged characters. You can place fire or ooze in the way to prevent them from marching through it, but short of smokescreen and surrounding them in fire to keep them blind and unable to move, they will circumvent every environment you place to get at your ranged characters.
This is where games with grid-based movement shine. Everything squeezes through the smallest nook and cranny if it'll bring it to the weaker targets. With a grid, the tank character can effectively bottleneck them, preventing the entire AI team from piling on the weaker characters.
I'm not asking for a means to force all the AI to do nothing but mindlessly focus my warrior, and the idea that a tank does just that exclusively is almost entirely a false concept erected solely around modern MMOs.
There are tanks in Pen and Paper games. There are tanks in virtually everything. You can set up a tank in Baldur's Gate, for example. You can even designate a tank in old school JRPGs like Final Fantasy, albeit simply by placing ranged characters in the back of the party where they take reduced damage from melee attacks.
Saying that it's insane for the AI to attack the target that's closest to them, doing the most damage to them, and giving them hell in close quarters is, well... insane in itself. It's absolutely insane of them to engage something in melee combat - only because they couldn't get closer to the mage in that turn - and then immediately break out of melee to go after the mage. The Man-at-Arms skills should have some way of guarding its allies, plain and simple. They don't need to be the sole target of every attack, they just need the most minute asset in party protection, and they're utterly lacking in this department in every way.
