To be quite fair, it is subjective as well as relative when considering the quality of a game's content. What you consider to be mediocre someone else will consider to be excellent and yet another will consider to be poor. I will also call into question your experience with games possessing RNG item drops. I remember spending months grinding out a dungeon for four sets of Onion Knight armor for Final Fantasy III. This is not something that is exclusive to Final Fantasy. Pretty well every RPG, that I've played, with item drops will encourage the player to grind for particular drops. I really don't see how grinding for drops in Destiny is any different from grinding for drops in those games. I would be delighted to hear the difference since I seem to be ignorant of it.