Well, everything has 2 sides. On one side you have "This is a dungeon that I despise, completely. I don't care how capable the rest of the party is I don't care and don't want to find out". These people might be able to entertain themselves while waiting of the lockout to be lifted and/or have really fast queues after the lockout is lifted. On the other hand we have "I don't care whether you like the dungeon or not, you accepted the risk of getting it when you signed up for roulette it in the DF". These people might not have a lot of time available to queue as many times as needed to find other 3 random people who are completely fine with the dungeon and/or have long queues which are not pleasant to sit and wait for (saying "craft, gather, etc." is not valid, because just like with dungeons, some people do not enjoy these activities).

The point is, people will always look out for their best interest. If you think that quitting a dungeon and waiting for the lockout is more effective/better than trying to do a dungeon that you consider bad/boring/tedious/long/dumb/difficult then good for you, you might have something else to do in the meantime and you are using your time effectively and you care about your gaming experience, which is completely fine. If you consider that doing a dungeon that you absolutely despise is the best thing to do (time-wise or for any other reason), awesome, you are actually trying to do something you might have had a bad experience with because you had a party that wasn't careful/skilled enough to do and you are also using your time wisely.

Sadly, it's a matter of what dungeon you get and who you get in your party. I know it could be annoying but it is how it is.