I did expert roulete the other day with 2 tanks and 2 dps the other day and we didn't miss the healers at all, in fact our clear time was no different from when we run it with a healer.
Instead of solving the wall to wall pulls and how it can destroy innocent healers who are either learning the role or learning a new healer job, square enix keeps designing every dungeon with 2 mobs between bosses. Literally almost every dungeon from level 1 to level 90 is designed the same way, and we call this the best mmorpg ever made? Hahahaha
Look, what xiv needs is new blood, new blood who's ready to create something new; what if the beginning of the Aetherfont dungeon was a 5 minute wave of polar bears which ended with a huge aether-drinking bear (coca cola reference) before you face the first boss? What if after the first boss you had to race, yes, you heard me right, you had to race penguins to the finish line as you make your way to the second boss; everyone in the party would need to outrace all the penguins or the entire party would have to re-race them again. What if after the second boss you had to swim underwater to catch 100 fish to summon the last boss?
I know I went off from your original point, but my point is that square enix is just bland and out of ideas. If they're worried about big pulls and how making squishier tanks would stress out healers, then how about not designing dungeons with big pulls anymore? Instead, introduce new encounters in content/dungeons where you don't have to balance healers and tanks around big pulls.
PS. Yes, I know tanks and healers are designed around ultimates, but one of their big worries is also the toxicity that occurred early on in Stormblood when they made tanks very squishy. I know a lot of you don't remember this or weren't around for this. But that's why White mage had a lot of healing skills during that expansion, they actually tried to make tanks squishy so that healers would start making use of all these oGCDs. But you can all guess what happened after people complained that tanks were too squishy? They gave tanks more hp and more defense. That mentality started the slow decline in battle content.
I still remember tanking and healing the first 2 stormblood expert dungeons and feeling badass healing or tanking all that incoming damage; it took good knowledge of the job you were using.