I don't understand why people are so irritated by AI party-mates. Enemies are controlled by the same "shit AI" also, it'd be more fair if you have AIs on your side instead of controlling everybody besides it making complete sense.
Because I like playing games more than watching games be played by the AI.
AI-controlled party members are ok in a game with combat like Arcanum's. Arcanum had super fast real time combat and not being able to control you companions was fine. I played it in real time and only switched to turn based when necessary. AI-controlled companions weren't irritating there.
But in any turn-based game, you want to control your companions because otherwise the combat is going to consist of you doing one thing, and then watching everyone else do shit while you just sit back. It reduces interactivity and turns companion turns into "watch and pray they don't do anything suicidal" scenarios. Lame. Slow RTwP games like NWN also should have companion control, because if you only control one character it's gonna be slow and boring. Not to mention the AI often doing retarded shit that loses you a fight.
Whether it's "fair" or not to have companions AI-controlled depends on encounter design. Most games with full party control throw enemies at you that require good tactics to overcome. BG2 has plenty of fights where you need to cheese the game to survive, KotC is designed around tough encounters. If your companions are AI-controlled, your encounters need to be easier because you have to expect the companion AI to do dumb shit. So instead of pitting the player against an enemy party with twice as many fighters and higher character levels, you have to pit the player against exactly balanced enemies that are roughly equal in number and level to the player party, because otherwise it's almost guaranteed the party AI gets itself killed.
And besides all the issues of frustration due to AI acting retarded, even in games with a good AI - heck, especially in games with a good AI that can challenge you on a tactical level - it's simply more fun to control a party than it is to watch the AI do things.
Performing a flanking maneuver with your fighters is fun. Coordinating two spellcasters to first use a vulnerability to fire curse, then throw a fireball in the enemy's midst is fun. Setting up suppressive fire with the heavy weapons guy while your light riflemen advance behind enemy lines is fun. None of that is possible when your companions are AI-controlled.
I'm a big fan of simulationism and realism, but when it comes to party control I don't buy the "it's more realistic that you only get to control your own character!" argument. So fucking what? It's more fun and opens up a whole lot of additional gameplay to control multiple dudes. Imagine playing an RTS where you only control one unit and everything else is managed by the AI. Would that be fun? I doubt it. Regular RTS games where you build a base and send squads of units across the map are fun, though.
If you don't want to give me full party control, don't give me a combat system that presumes to be tactical. Give me something quick and dirty like Arcanum or something action-based like Diablo instead. But if you give me anything with a turn based or RTwP system, I want to be able to control my party.