I think it comes down to the dps driven meta. People want it removed to avoid:

Losing damage by having tank stance on when needed.
Or conversely, not wanting to have to deal with tanks sacrificing the defense and enmity boost it gives while they squeeze out more damage.

Personally I'm not much invested either way but the tank I play is PLD where, aside from the damage in/out reduction, the only difference in our oaths is how we build our guage up. So I wouldn't be missing too much gameplay wise if they took it away, or just say made it only affect enmity generation. WAR and DRK I think would need more involved changes.