https://na.finalfantasyxiv.com/pr/blog/002618.html

Those were his words! FFXIV and... mahjong? Well, this was a request from the director and producer himself, so naturally the dev. team began to look into it. It required a bit of extensive investigation though, as FFXIV is a global game and regulations differ across regions.

Sure, it may seem like a harmless addition, but different countries and cultures have different perceptions on games that could be considered "gambling". This is why Yoshi-P's original idea to implement poker in FFXIV hasn't come to fruition yet, but he's thinking about putting it in one way or another...