The issue is that people want to know how much work they have to put towards something before they attain the reward. If you feel like this is irrelevant I don't know what to tell you. You seem really obstinate about it. But I'll try.
There are a lot of people who have issue with the system; even in the case of RNG, most systems have ways to measure how long it will take. A good comparison is the legendary quest chains where you kill a boss and have a 50% chance to have an item drop, and need x amount of them, as opposed to the final raid boss having a flat % chance of dropping the legendary. In this way, you know -- roughly -- how long it will take to get the legendary and plan around it instead of just praying it will finally drop for you.
Hell, even bonus loot chances and all sorts of things have been added because pure RNG is horrible. There are a lot of people who dislike systems that focus too heavily on RNG and this is no exception. If you have no issue with it, that's cool, but you are certainly not the only person playing this game. There are plenty of people who prefer other methods that use less random and give more of an idea of how much work is required.
Go look at how people felt about the Time Lost Protodrake and the Green one that dropped from the egg in Sholizar Basin for great examples of how bad the RNG system can be. It's always more enjoyable if you know -- or have a vague idea -- of how long it will take you, instead of "it could be today, or it could be years later" -- or in this case, an hour of gameplay weeks of gameplay. Most people would simply prefer to know they need to work a certain period of time instead of potentially dumping tons of time into something that may never show up.
The simplest way to put it is that some people like to work towards a solid goal. I do not know how more simply I can put this than this.
Regardless, I can respect your opinion. If you feel it's not necessary, that's fine. But if you cannot even acknowledge why people might feel this way, then that is simply crazy. That is an extremely narrow view on mechanics. People not wanting to put in the work, and people wanting to know that they'll get something out of the work for certain -- specifically within a certain amount of effort -- is dramatically different. Pretending the two are one and the same is a tremendous logical fallacy, and highly irrational thinking.