Now I see where you're coming from.
Well, in my opinion, rotation, as any routine, is only possible when your actions are not affected by situations.
Just like if your only instrument is a hammer, then everything starts looking like nails.
If your goal is to deal maximum ammount of damage per second no matter what, then you chain attacks in the same "most effecient way" way all the time to make use of the timers or make the best of your resources - so not much difference between cooldowns and mana-pools from that point of view.
I hope that PoE would provide enough tactical challenges to make us want to use abilities other then the ones with "maximum damage".
Personally I don't mind cooldowns (although, I prefer to call it recharge) as long as it makes sense.