People pay 25$ for menus in a fast food or 15$ for a single t-shirt. Others enjoy buying a Fatter Cat mount or outfits in a MMO cash shop. I don't see the problem to be honest.

Yes, things could be cheaper. But I don't think me paying my subscription entitles me to anything. Why ? Because we have mounts in game, we have outfits in game, we have emotes. I played many games before where, for exemple, you had access to ONE default mount. In the entire game. Oh, you want something new ? Well dang, pay for it. And that's really shitty.
At least in FFXIV, we have access to so many mounts, throught many quests and challenges.