So TLDR: OP wants to turn tank stances into a what healers have with cleric stance? No thanks.
The fact that people regard tank stances as "useless" in the first place is mostly due to the game design. Boss fights have tank buster intervals at set times with auto-attacks and/or fluff damage in between. So it is easy to predict when you need to use a cd and how to rotate between them. If bosses started using tank busters every 30 seconds suddenly you see the value in staying in a tank stance for that mitigation, and healers will have to focus more on keeping the tank alive. A hyperbolic example to say the least but damage in this game is so negligible outside of tankbusters I'm not surprised that people don't see the value of tank stance anymore. There is also the fact that shirk changed the game where as you need to be in tank stance to get enmity now you don't since the OT can just give you their enmity.
I personally see no problem with the current way of how the tank stances primary functions work, one dealing enmity and one dealing damage, outside of the lack of creativity. I mean DRK/PLD stances are just constant rampart buffs with damage penalty. WAR got lucky with the creativity but just because you don't use tank stances as often doesn't mean its useless. There is a reason why WAR always pulls with Defiance Unchained because enmity is still important and the recent 4.41 blm buffs are no joke with a pro blm. The devs created this problem, not the players.