Somehow Bioware forgot to put the auto attack in the console version. They released a broken game LOLOLOLOLOL.
I wondered about this when I played the demo. The constant A button tapping was ridiculous and didn't serve any purpose. It would be one thing if you could string attacks together and combat got more complex but everything in the demo was just an auto attack animation that required you to press A constantly. I never went looking for a way to turn it to auto-attack, I just moved to the mage character and started casting spells which broke up the constant button mashing.
Quite embarrassing for Bioware, if you missed something this big what else will you have missed.