Bring back Aggro, resource management, bring back consequences!

[Lyth]

It's not hard to come up with ways to make an engaging tank fight.

Regular boss autos (perhaps they occasionally crit, or is that too ambitious?), coupled with a cleave pattern that you need to memorize and mitigate with your short recast cooldowns. Bait out the invulns such that players are forced to use standard mitigation for tankbusters. Perhaps have a mechanic that requires the use of an interrupt to make it more survivable. Lots of movement, either through a need to keep two mobs separated (cat phase), to dodge aoes (Aiatar), or due to a shrinking destructable arena. Council fight with interesting swaps. Maybe have the bosses swap tanks, Stalagg and Feugen style? I've always wanted to do a double arena council fight with a gravity mechanic where half your party fights on the floor and the other half on the ceiling. What about an aggro reset mechanic where the bosses dive a healer and you have to peel for them? There are so many ways to make fights feel fresh and interesting if the starting point for your design is 'how do I expect this to be tanked?'

Or you could have a massive boss that sits outside the arena, positions itself, and spends most of its time casting AoEs outside of two tankbusters that you invuln-swap out of. I dunno, I really don't think that bringing back TP and waiting for three sunders before starting to dps is going to improve the quality of that sort of experience.

[MerlinCross]

There are so many ways to make fights feel fresh and interesting if the starting point for your design is 'how do I expect this to be tanked?'

But it's not and I don't think it's ever going to be. The starting point seems to be "What cool things is the boss going to do?" And then the players get put into the arena.