This would cause so much shit. It's incredibly easy to abuse for competent players. Get a key to 14 and start doing it by opting out of the timer. So. Much. Free. Gear. Simply because competent players can spam the living shit out of it and offset the fact that you get the rewards of a failed key. If you can complete a +14 twice in about the same time as you complete a 15-16 or higher as a failed key, for example you would get all the gear you need. Not to mention that people will perfect it to the point where it'll be so easy some weeks people will be pulling half the dungeons.