I don't think someone purposefully DCing is an Examplar either. But they play the game and pay a sub like anyone else so their opinion is just as valid. I don't think them doing what some consider rude to change that. A lot of people don't want there to be a penalty for leaving in any game. I've felt like I'm being held captive in an instance on more than one occasion in this game and others. Yes there is the leave button, but why should someone be penalized for trying to get away from what they perceive to be a toxic situation? The system has no way for detecting this which is another flaw within it. I don't think trying to get around that makes someone a bad person. Since getting rid of the penalty is probably not the best idea I prefer changing up the content selection in roulettes. "Oh people leave this a lot? Maybe we should remove this instance from this Roulette and put it somewhere else?"
Saying "just don't que" is the easy answer and one that does not satisfy me just like the "fill this missing spot" perspective does not satisfy you. Ultimately this comes down to which is more important the status/expectation or getting clears and not upsetting people? I lean towards the latter as I don't expect people to rise to the occasion; therefore I don't ask them to.