The moment you stop having a sub for something like FF14 (which has no in your face upsell garbage in-game), you turn in to something like LotR: Online (which when I played that briefly was FILLED with windows trying to get you to buy gold or other nonsense).

You pay a sub so the servers stay online. So the writers/coders/management get paid. In the case of FF14, so the game can continue being great.