17 years of WoW. That's nearly an entire generation that has been playing, and they're not going to want to give up all their achievements, all their transmogs, all their titles, all their guilds, all their feeling of superiority, just to play a new game, even if it has the same engine. There's a bunch of other reasons, but those are WoW specific.
Imagine if FF made the "World Reborn" decision *now* rather than when they did. Given all the investment people have made in the game, not just monetary for items and such, but time as well, how many people would really come back? FF is going to be facing the same kinds of issues that WoW has faced fairly soon - the barrier for new players to get into the game. It takes time to get to a level where you can play with all your friends who are already in the game, and then to discover (as I did) that pushing the MSQ at the expense of everything else, means you can't do the Raids on the duty roulette. It's going to run into a whole host of problems with increased item levels, and continuing to make content that is interesting, and challenging.
It could be that SE will say "We don't care, let them buy boosts or level slowly." Which is fair. But it's the design decision they chose to make, and I wonder how much they're thinking about what the next two expansions after Endwalker will be like. Where do we go from there?
