Alternatively SE could remove Diversion/Shadewalker and all the non-tank aggro dumps, and improve the auto attack damage of bosses in savage enough that tank stance matters for a significant period of the fight. Currently cooldown management is the only thing required. The emnity required to keep ahead of the DPS and healers would be enough incentive to care regardless, and the extra auto damage would put more pressure on the healers, resulting in more of a net loss in DPS if tanks overstayed in DPS stance trying to get their damage in.
To me, requiring tanks and healers to balance their DPS contributions between each other is more important than letting tanks go full stop on damage. Healers should be hitting harder than tanks by default if left to DPS fully, because tanks will always be dealing damage even in tank stance. The raids put more than enough pressure on the healing side as it is, and not enough on the tanks themselves. That has to change. To me, that means nerfing tank dps (preferably through indirect means, such as forcing stance swapping in order to maintain emnity) and making them care more about mitigation, and increasing healer DPS and giving them more ways to do so that also cost healing resources. The current state has tanks dealing more damage than healers even without factoring in how actual fights play out, and that's not a good state to be in. It's a sign that tanks need more pressure in general, and healers may need less, in order to facilitate spending their resources on damage where possible.