First of all, Mahjong is a time-sink game to begin with at first place.
Second of all, it is not a mini game, it is a complicate strategy game developed by Chinese then populated to Korean and Japan just like Gon. It is never mean to be a faster game.
Third, Mahjong may seems to heavily rely on RNG, but it is actually skill based. A real Mahjong master will screw you all over if want to.
Lastly, who said mini game must be attend to western audience? There are a lot of mini games in golden saucer I dont even give a damn for. Did you ever see Asian players complaining about these mini games are not for them? This is clearly targeting Asian audience. I am pretty sure this is a feature welcome by Korean Japan and China FF14