Eh, people will play to the standard that the content expects of them, sure it'll take some time and absolutely there will be people that moan about it no matter what direction things take, but at the end of the day, people will adapt.
Don't forget that we had a time in the past where the level cap dungeons had enrages and stuff would actually merrily kill you if people dropped the ball.
Also don't forget that if you go back to HW/Stormblood, that same player likely wouldn't have been casting nukes either. If dots get more important again, people will gradually adjust and warm to it. Stifling development progress over unimportant metrics such as a casual healer forgetting to refresh their dot in content that doesn't have an enrage timer is self defeating to the max.
People adapted to the likes of Cutter's Cry, Qarn and Amdapor Keep, they'll adapt to dots becoming more important.
On a sidenote, SE could also help things by taking more inspiration from the forbidden addons, there's one that pretty much doubles the size of your own debuff icons on a target making it much easier to keep track of dots if you don't have the timing down. Other routes include something like self only auras for dots to make it quite visible on the target when it drops off or even a distinctive fall off audio cue.