True, but what's to keep them around once they get the thing they want? I certainly wouldn't stick around for months if there was nothing to do the entire time until the next patch update. First and foremost, this is a business... one that they want to keep people invested in the game realistically. If people feel satisfied with the game, and feel they have everything they want from it (even if it's just until the next patch), you'll generally move on. It's not quite so linear of a thought that needs to be considered as you might believe it is, where all they need to worry about is giving people everything when they expect it.
Why do you think F2P MMORPG games never retain a large dedicated player population? There's many reasons and only a few deal with RNG. It's all about the psychology behind the marketing and design. Unfortunately, psychology and how to manipulate the pleasures and drive of people is too complicated for most, so they'll go on believing that things don't have to be a certain way in order for it to work as a business/product, when... that just isn't how it works if you expect success.
Exactly, people can find anything fun if it suits their style. But... think about those games you're referring to, then think about where they stand now as an MMORPG. Are they catering to as many people as WoW? Or FFXIV? I'm willing to bet no. You're right that the beginning part of the relic quest was great. But then what? What could they do to have kept it in line like that without making it the faceroll that we look at Zenith as today? It's just like the Soldiery weapons, it is now the norm go-to weapon because of how quick and simple it is, just as the Zenith weapons were looked at prior. You folks only look at things for the immediate sense, not for the long term. I ask again, how would they go about making such high end gear available without it being a quick and faceroll process? If all gear/rewards were obtainable as fast as it was to get the Zenith weapon at any point of FFXIV, I think we'd be bored very quick lol.Sure, it CAN also be boring, if you get everything for free (though there are enough games without leveling and equipment to buy, which people still play, because it's fun to play them), but really:
Beside the lag problems at Titan, the first part of the Relict Quest was the best. No grind at all. A challenge, but no grind. And no RNG (well, a little bit, if you take the weapon material drop and the materia, but that was within limits).