Here is the catch that I think people don't understand: Most Japanese players do not own what would conventionally be called a "gaming" PC. The PC market in Japan isn't really a thing at all. It's kind of there but it is vanishingly small compared to the handheld/console market.
The PS3 launch of FF14 was instrumental in getting the Japanese players on board with ARR. It may seem like a very questionable decision now, but no small part of the game's success in Japan is owed to it being available for console players. Because like it or not, that is their market in Japan. One of the primary reasons 1.0 failed in Japan was lack of a console version; it was PC version or nothing
They would need to offer PS3 players a very big incentive to move to PS4 or PC; it's not OK from a business perspective to just suddenly turn to a chunk of your playerbase and say "sorry, you need to buy a $399 hardware upgrade now to keep playing the game."