The problem causing more people to gravitate to DPS is that the encounter design is based on defeating adversaries for experience points, reputation, and loot. No matter how much you try to cover up the underlying difference in damage, people gravitate towards DPS roles because they promise to accomplish the primary goal of the game faster. Healers are more popular in FFXIV than other MMOs primarily because their damage output during the leveling experience is roughly on par with the damage dealing classes, making the conjurer/White Mage and arcanist/Scholar more appealing because they can bash things faces in just as well as any of the DPS. So for most of the game, the healer role plays more like the beloved "combat medic" people find in many group-centric First Person Shooters, where the combat medic can kill things just as well as the rest of them, but when a buddy looks like he is going down, the combat medic's specialty is keeping him up.

Tanks on the other hand have markedly lower damage when in group because the abilities that allow them to survive getting wailed on also reduces their damage output, making them hit like a wet sponge. So we have this guy with a giant axe using flashy special moves, but the payout is still so obviously less than the DPS he is playing with.

Standard RPGs can get away with these kinds of conventions because the player is controlling a team of characters instead of a single character, and the fact that the game doesn't last nearly as long. You simply can't hide the underlying mechanics in a game where people are going to be playing for years, so it is important to have an encounter design that rewards all roles equally.

And the scary part about this is that I've been making the same complaint about the holy trinity for about ten years... which is only slightly shorter than how long I've been playing MMORPGs. Can we get rid of DPS as a specific role already?