They're not complaining about it because it's the oddball of the process. You're really not looking at how the process itself is because you're comparing it to things that are approached differently. You have to compare it to maybe tome gear or acquiring gil. Trackable resources that are used to getting these things. Then apply how you get them. Believing people enjoy the books for what they are in general is really ignorant and very biased. Even your mention of the lights falls into this perspective. How many people ENJOY (keyword there and one that you apparently replied to) the process? Your happiness while you grind to the goal is no different than it is while you grind through RNG. Enjoying something is not the same as thinking something is easier. Huge difference there. The only defining factors is that you know there is an end when there is no RNG... doesn't mean you're enjoying your time to it though (again, no different).
Again, as I pointed out in the earlier reply, just look at dungeon runs and how ridiculous people become about negatively looking at an instance taking 1 minute longer. About how long it takes to get MGP, a trackable resource. About the cost of housing, a trackable goal and resource (gil). The complaints/boredom/anger/etc that sparked RNG hate is still there, it's just redirected. I guess there's honestly no point to convincing people why a system exists when all they care about is their own satisfaction and how their own impatience is causing a clear sense of bias. One could argue defending the existence of RNG as being selfish, but those arguments aren't ignoring what category/genre of game we're talking about here. Nor is it ignoring the business side of things (the sole reason the game even exists). Mind you, again, as I said, there can be too much RNG involved, but that depends on the time allotted for the content to exist and the future prospect of nerfs in an MMORPG.