There so many things with what you said that do not work in a classical tab target MMO... and a lot of these things that you said only really work in a action MMO like Black Desert Online and Phantasy Star Online 2 just to name a couple examples... and because Final Fantasy 14 falls into classical tab target MMO, that means a lot of the things you are okay with only work in the short term and MMOs by design are to you to play as long as you possibly can without playing anything else because it also has the pay-to-play model that somehow has free-to-play elements that do not mesh with the payment model it's using(see World of Warcraft in how it is struggling) there is also the fact that unless there is a steady flow of money going into the game any other projects are going to be delayed or canceled if keeping the MMO up is top priority... though this isn't the thread for that discussion...
Aggro management is probably what made the mechanics that are just the boss auto positioning for some kind of attack less boring than they are now as it was something you still had to pay attention to whiles also making sure that bosses didn't just 1-2HKO someone that wasn't a tank from auto attacks alone... and you could do any content without Provoke or "tank stance" and it will yield the exact same results as using those abilities and chances are that 1-3 people are going to get upset that I even remotely suggest something like that and the devs see that as 30,000 times the amount of people getting upset about it and listen to them and force enemies to tether to the tanks just people stop complaining about it...
Bosses just auto position for the players, and by 6.0 aggro might as well just tether to tanks automatically, further alienating players from what made them go to the role of tank in the first place, tank busters and raid wide AoE damage might as well not exist considering how infrequent they are becoming, tank swaps become even more pointless because, again, how infrequent they are becoming, and even trash mobs in dungeon dungeons might as well be training dummies that do damage but don't move, and any mechanics that bosses would have had are just replaced with auto-attacks and everyone (with the exception of the small handful that are okay with it) will ABOSULUTELY HATE IT which means the devs and Square-Enix would need to do damage control but by then it would be too late to save FF14, and yes the devs WOULD do all of that JUST TO SPITE US PLAYERS AND FANS... and it's not a matter of "if" but "when" it happens... and WHEN it DOES happen; I TOLD YOU SO!