I don't see what's wrong with RNG here. Alternatives would be to clearly label all asteroids with their contents or make them all the same. Both dumbing-down the game.
Additionally, there's already several visible overlays on the generation
- ring type
- system reserves level
- hotspot presence and type
- RES presence and type
No matter how lucky or unlucky you are, you're going to get considerably better results in a pristine metallic ring than a depleted rocky one.
Leaving aside the ability to map the rings completely - which given the effort required to produce the map and learn how to reliably read one, isn't even necessarily an "exploit" when viewed in the long-run - even once you get to the mining site there's several ways to manage the randomness:
- do you take a single prospector just for the improved yields, or do you take several so that you can be scanning multiple adjacent asteroids while your (fewer!) collectors work, or do you mine in a wing so that one of you is prospecting for the next great rock while the other three mine the last one?
- do you take a large refinery and collect everything, filling up your hold quickly for reliable earnings, or do you focus on a few high-value types which will usually give higher earnings overall, but risk having a bad day?
- do you go for the steady profit of laser mining Platinum/Painite/Osmium, or the much more variable profits from core gems? (much more valuable per tonne, but significant opportunity costs to finding the right sell locations)
Noting of course that provided your ambitions are "tens of millions of credits per hour" rather than "hundreds of millions of credits per hour" the answer to the above doesn't matter - drop randomly in a pristine metallic ring, start mining, you'll end up a fair bit richer at the end.
"Managing the range of random events to come out ahead in the long run" is the fundamental game mechanic of a substantial number of games, and a major one of an even more substantial number - though there are plenty of people who insist on only playing games with no randomness, the Elite series is hardly for them (ED is
less random than its predecessors in a lot of areas, of course).