Editing this: You've humored me enough so I should be kind enough to do the same.
You keep saying you're satisfied with how tanks play, and claim it's only a numbers issue preventing your enjoyment, yet we still get posts like this where you highlight how little there is to do other than mindlessly punch out the tank damage rotation.
I'll clarify and say none of the 'rotations' themselves in this game are that complex. The most demanding of them belong to the Ranged role generally, as they're dynamic and priority based, so what you need to do at any one point can shift.
You heavily misrepresent your tanking responsibilities even in the current tier of raids. It's not just a 'mitigation button', but for the most part, it is fair to say that tank specific responsibilities have been reduced.
The thing is, I place that blame squarely upon threads like these, where the community gives voice not to more demanding tank mechanics, but to -more damage-. And not even more damage in give-and-take manners. Not in ways that expand the Tank's moment to moment gameplay.
Acceessories. Accessory scaling. Tank stance penalty. This thread.
For all the talk of how SE doesn't listen to the playerbase, they ignore how often SE eventually caves - And how little things actually change, insidiously clever as they can be. So I haven't taken you at face value. For that I'll apologize.
Your issue of active vs passive contribution is one of perspective. There is no effective difference in you hitting rampart and the white mage hitting Tetra. You hitting Living Dead and them Benediction. The claim that healers are rewarded with big heals is misguided, because it's not big heals that the healers are rewarded with, it's the opportunity to do damage.
Their primary function is to heal. By succeeding at their primary function, -the party lives-. By excelling at their primary function, -they have to do the primary function less-. Nowhere in this reward schemata is the Heal itself the reward or the incentive to heal better. It's the ability to deal damage without risking the party. They cannot live harder if the healer heals harder. At some point it's waste. The task is to heal. The better they heal, the more damage they get to do.
The tanks primary function is to control the encounter. By succeeding at their primary function, -the party lives-. By excelling at their primary functions, -they enable the party-. While responsibilities have been minimized (Again- I blame threads like these), to completely leave them out and say "tanking is just hitting a mitigation button" is disingenuous at best.
Both the tank and the healer have primary objectives that -are not damage-. Both the tank and the healer have a -very high second priority- in dealing damage.
There's no objective reason they cannot be shoulder to shoulder. Tanks and healers are both indispensable to the success of the party, and however little you feel you contribute, you get four slacker tanks and healers, and everyone's feeling the stress that brings, no ifs ands or buts about it.