Would we all like him to fill his downtime with DPS? Sure. But these are SUBJECTIVE standards, set by every individual. We do not have the right to enforce them (via vote kick etc) unless the game agrees via design and makes it an OBJECTIVE standard.
But already do this. Classes have skills that are there to be used when appropriated. If I queue with my friend as tank and healer and decided to pull wall to wall a DPS not using their AoE rotation, made easier during this last expansion, is not playing at the basic standard set by the game itself.

In short, refusing to use the skills your class has (included cross-class skills) is refusing to play at the standard level set by the game. Using all your kit is just that a healer refusing to do use DPS skills when appropriated is as bad as any DPS refusing to use Feint/Addle.

Anyway, the pointless discussion IMO. Anyone caring enough about this issue should stick to play with in-game friends, randoms will be randoms, particularly in a game where devs are aware of the skills floor problem and are actively trying to fix it by simplifying existing jobs and making the new ones very newbie-friendly.