I think the approach to self-sustain taken this expansion is flawed and uninteresting. The appeal in lifesteal comes down to skillful execution and surviving against all odds. Building in heals and regens into actions that you press all the time doesn't really develop that skill execution. It just creates situations where tanks are either 0% or 100%. Self-sustain needs to be deliberate, and be timing dependent. You only really get a sense of risk if you're constantly in the bottom half of your HP bar. Tank sustain needs to be revised, not just for the sake of healers, but for the sake of tanks as well. This comes back to that platformer without pitfalls analogy.

While toning back self-sustain on tanks is important, I don't think that resolves the discontent that healers have been expressing for a few expansions now. Increasing healing requirements will make your progression experience more interesting, but not necessarily satisfy you when you're farming content. If a large portion of your toolkits is dedicated to defensive actions, then you'll never have a dps rotation that's going to provide the same level of engagement as an actual Caster. Utility actions like Expedient that can impact team performance/uptime are another question, but one that is largely unexplored. The question around whether resource management could be made more interesting is another. I think the problems run much deeper than just tank design.