Sometimes, we're fighting monsters a lot weaker than us (farming, easy quest, etc) and we pretty much use the same attack every single time until the monster's dead. This gets a little annoying.

My suggestion is that there is an "auto" function for repetitive attacks. For example: activating the auto function for "attack +25%" will make my character attack the monster until I either disable this feature or the monster/I die.

It will not unbalance things in any way – it will simply make things a little more convenient.