Have to define bad game play.
Was FFXI bad... highest gross profit FF game, was in the top 3 mmo for over 6yrs in terms of population only fell below 5 after Aion I belive, held almost its entire playerbase for 8yrs. Only Existing mmo that WoW didn't destroy population wise more or less after it released.
ATM you have 3 scenarios:
1) Old School Grind: Current Gen Western players hate it (Asian grind is what most people consider it now days)
2) Newer Gen: Repetitive Solo Quest Grind (honestly just as bad as option 1, except you are playing an online mmo like a offline one)
3) Current Gen Western games: You get to endgame with quest really fast (WoW's Style now days... can get to cap in 1 week if you are a semi-hardcore player, makes the game way to fast)
Honestly all 3 of those fail in their own way. So what is broken and what isn't. One caters to those who hate grouping the whole point of an online game, one caters only to those who have a lot of time (ffxi/eq style), one caters to those who want a offline experience who hate waiting and want instant gratification.
Atm you have an issue with XIV.
-The current FFMMO players for the most part want a party centric game with the option to solo when they are low on time. Solo Quest based Leveling will not work in this case.
-You have people who came over from the WoW age, who want well mainstream western style (WoW's quest based leveling system until endgame where you group for raids)... Grind Partys are looked down apon here. And the people who want to party simply will quit over this, Solo quest grind forces everyone to solo.
Only Solution: Offer multiple options. You cannot screw your fanbase over and but you also cannot ignore Westerndestructionadvancement of the genre. (Depending on your point of view)
You want to do quest this game needs to have them, but you need to level alot slower. You want to play a mmo (socialize and stuff) then group up and get there faster. You want crazy fast progression buy XIII-2 and stop playing XIV (MMOs are not suppose to be fast). They are even adding group quest thing to sorta combine both sides.
Your opinion of FFXI being bad game proves more or less your ignorance. It is not your cup of tea, but is also one of the worlds most successful mmos and there are a ton more people then you think who want a party centric mmo, so many are sick of WoW clone after WoW clone. I mean that is what a mmo is all about the community, this genre is not about solo quest.