Two words Trion, Key Ring ! We go through the time sink with the disguise etc to collect the keys once, the keys go on your key ring and you don't have to do it again.
You can even make the key gathering a separate quest to gain entry to the instance. The keys, again, go on your key ring.
I'm sure this is not news to the Trion devs as many other games use this device. Forcing people to go through the entire time sink every week is just dumb and gives ammunition to people who say Trion is adding more and more grind to the game.