No and yes.
We should cut down sustain on tanks, but theirs actually more to it then just that, I've said on the post above tanks like warrior need a overhaul in defensive/healing kit, PLD/GNB need to be tuned down, but we don't just remove sustain from tanks and call it a day "healers are fixed"
I will not be happy until both roles have a actual place and have actual decision making, Tanks and Healers both should be treated as support roles and should serve the party in ways that boost the survivability without invalidating one another.
What I don't want is them to up the tanks mitigation value more and just make them boring mitigation bots when we have ZERO enmity management. That is not why I play tank I play tank as a fantasy of "protector of the team".
Mitigation is a large reason why tanks are too strong, fight designs low output is and sustain way too strong, all three need to be tuned with healer kits in mind.