I think that auto-attack would be better if it stopped when you lost armies, but continued to roll each time you win 2: it would be an effienct way to attack territories that you intended to conquer.
I don't think that there is anything special about auto-attacking. The risks you take are the same as if you hit "attack" several times in a row. I don't think that this reformed auto-attack would necessarily exclude any risks that make the button special.
I am unsure about how the stop mechanism would work. I know nothing about the random number generator. Why couldn't the system stop after a pre-determined number of armies were lost?