I don't think that toggling Passive/Active states should be automatic. It helps with camping and reaction time if you can do it on your own.

You can either:
A) Target a mob, ready an ability, wait to automatically enter active mode, use the ability
-or-
B) Enter active mode before you need to, ready/use an ability

The delay isn't HUGE, but it's enough to where not having it can increase your effectiveness.

Also, you won't auto attack if you don't have your skill bar up, so you can enter active mode, approach an enemy, then just stand there if you want. You won't swing until you hit enter again to bring up your skill bar. Granted, if you don't know your hotkeys, you're going to have a harder time than someone who can hit the hotkey and back out of the skill bar.

For mages trying to sleep, hit the sleep hotkey, enter for your target, then just hit ESC to back out of the skill bar and you won't attack your sleeping target.