There's not really anything they can do about that: In each and every fight in this game, you "Win" if the enemy HP reaches 0, which requires damage and nothing else. As such, it has an innate supremacy in importance over anything else. Healing and Mitigation are useful, but only insofar as that they allow you to get more damage in, which goes over countering the damage that you cannot avoid taking. And just that damage, not more.
Except they're already so immensely powerful that we need to have hard enrages to limit their power. Worse, since healers are so immensely powerful, a lot of mechanics in so called "non-faceroll content" are insta-gib or otherwise crippling mechanics to prevent the healers from nullifying them - which in turn also makes it impossible for them to allow Damagedealers to actually deal more damage by allowing them more uptime, which however is the only way for more healing than is necessary to counter the un-avoidable damage to be useful. Even worse, they can deal non-insignificant damage themselves, so even if they COULD allow Damagedealers more uptime, the benefit of that would have to compare to the Damagedealer just doing the mechanic right and the healer DPSing in the meantime. And tanks got it even worse than that because even the best mitigation at best can only increase healer DPS, not that of damagedealers.
And that's not even going into the issue of different skill levels and overgearing - If you make a good tank only tank, a bad tank will just die. Similar goes for healers. If a healer in i270 can't contribute much DPS, a healer in i250 will likely just fail. But if you tune for a lower level, DPS supremacy kicks in -> Hello DPS meta old friend!
The only thing they can realistically do about that meta is to design fights in which damage isn't needed to win - which in turn would make Damagedealers and like 80% of all skills obsolete. They can try to nerf healing and tanking into oblivion so that only great players in those roles can do more than focus on their core, but that would be highly unpopular among established tanks and healers and would likely deter new players from joining these roles as well. Other than that? Not a great many options.