Auto attack would be nice. And it's not too late for Beyond Divinity! Personally, I like the system in Neverwinter Nights. The player must initiate the combat, but after that, the target automatically shifts as each foe dies. I don't think it should be fully automatic. The player should have to see the monster first, otherwise it just becomes too easy and lacks player input. Attacking in retaliation would make sense.

It might be a problem for Beyond Divinity as there is more of an emphasis on limited ammo (arrows, mana). Unless you have a melee weapon drawn, you could quickly and unexpetedly run out of attacking power. Even melee weapons can have charges (eg. poison). If it's added, it definately needs to be optional.

Check out this thread: Auto attack

And welcome to the forums!