As a healer, I also appreciate that we have more interesting stuff to deal with. So, consider this a +1 on that.
I do think there's one (minor) downside, inasmuch as it magnifies the existing flaws in the current server tick system; I can be in a fight with my static (so same people, same gear, same strats) and like 1 out of every... say, 12 pulls, we'll hit the timing JUST right so that the first post-tankbuster auto and the first DoT tick happen simultaneously, and the tank's health just evaporates.
Right now this doesn't generally lead to a death, because my co-healer and I know to watch for it. But it just gives me this faint worried feeling of "hmm, I can see this might become a serious problem in some future fight."
I think this is partly a result of them focusing more and more on mechanics that require precise positioning; if the mechanic needs to line up with marks on the floor (P1S Intemperance, P6S Polyominoid, basically the entirety of P8S phase 1, etc.), they seem to want the boss to be positioned appropriately to let the party focus on the mechanic. There are exceptions -- I feel like P6S lets the boss get dragged around the arena during a surprising number of mechanics, even if she resets to center to start the mechanic -- but in general, they seem to want to shift back to center and lock there.
(As opposed to older fights, where... well, we've all seen what happens if a tank pivots Calofisteri the wrong direction in Weeping City, causing a "half room" cleave that renders ~97% of the room uninhabitable.)
I do rather suspect that if they didn't do this, of course, we'd have a half-dozen threads on this forum complaining that tanks are terrible at positioning the boss in P8S phase 1 and you can't keep uptime and so can't make the DPS check, or tanks complaining that DPS checks need to be lighter or mechanics less unforgivingly one-shot so that there's a little leeway in positioning, etc.
But in the end, I agree with you that it's less interesting. And more to the point, it also gives a tank less options to help optimize for others; in current fights, a tank basically has responsibility to mitigate and hold aggro, and to execute mechanics alongside the rest of the party. Whereas in older fights, a good tank can often position things cleverly to speed the fight up for everyone, like how you can help folks not have to do the mechanic by pivoting Calofisteri the correct direction in Weeping City (and cleaving only off outside of the arena).