As a Quinn main, this encourages playing her bad. If you are always hitting marked minions you will push way to hard, and if you are always using ault you are constantly putting yourself in a postion to be engaged on. Proper use of harrier isn't just hitting it as much as possible.
I'm really not sure a shorter ult cooldown is needed anyway. Quinn is in a pretty good spot. Most of her issues come from her having a unique play style that most people don't understand, or use properly. She isn't really a marksman, sure you're ranged, but the play style (even without ult) is more assassin like, and with ult up you have talon or zed levels of burst. Her ult cooldown is longer than that of talon or zed because while it's on cooldown she can still safely deal damage whereas talon or zed is just dead.