I wouldn't dream of requesting to be kicked if I had used roulette to get into a dungeon, if fact I can only name 1 time when I have left a dungeon and that was in the first week of 2.0.
If I enter a roulette, I always give it my all, after all, I chose a roulette knowing full well that I might get a dungeon that I may not enjoy as much as others.
IMO, if anyone enters a dungeon and then changes their mind, or they need to leave for other reasons, then just leave, take the penalty and go.

I do not agree however, that a vote kick should get a penalty, my reasoning is that since Heavensward started, my DC rate has increased ten fold, before HW I probably only DC'd once every 2-3 days, after HW I now get DC'd approx 3-4 times a day, so I would not appreciate it if during a DC, I get vote kicked and also receive a penalty for something that is beyond my control.

I think a more appropriate penalty would be that if a player is inactive while inside the dungeon for a certain amount of time, then they would receive a penalty, so anyone that doesn't want to leave because of a penalty would also be discouraged from just sitting around and not participating.