DPS Stance vs Tank Stance Including Healer DPS

[Reynhart]

They simply aren't fun.

I'd say they don't really have to be. They're just mathematic adjustment to your damage taken/dealt. Gameplay don't have to be related to the stances.

In order to actually fix the issue you're referring to (that turtling isn't viable aka damage > all) encounters would need to be designed on some other formula for victory.

Some gimmick encounters could be, but it's not necessary. Since what matters is raid damage, one "easy" solution is that what you lose as damage can be compensated by the other party members. For healers, by giving more room to DPS, or DPS risking ripping hate and thus having to hold back if the tank don't build enough enmity in DPS stance.