Correct me if I'm wrong, iron arrows are only useful to the Outlander? Otherwise, you need a bow, a skillbook that teaches you to use them outside of combat, two arms(?), and iron arrows? The iron arrows can help the Outlander, they're nice to find, but I fail to see how the RNG is helping much in this case.
Something more to point out, is you search probably three hundred containers over a play-through. This actually makes for less RNG in relation to loot, it should balance it out so you always get roughly the same haul. In the games mentioned, they tended to have rather few treasure rooms, which could hold amazing buffs that stack together, or just reasonable ones. This made for a greater sense of RNG, positive RNG.
Beartraps are cool, not debating that. But, is that what you meant by being able to find the best equipment at the start? A couple of bear-traps? Those are one-use items, and can't be used against most of the bosses in the game. Their best use is just holding off Crow Mauler so you can get past him. Though, running away after you enter combat works pretty well, too, so I'm not sure they're even that much help.
Explosive vials are pretty rare in the early game, if you find one you can use it to speed-run pretty effectively. Extras are nice, as they do work to make most fights a lot easier. So, I agree... if you find a dozen explosive vials at the start, the game will be a lot easier.
Don't you think that is a pretty specific scenario of RNG helping? In the examples I gave, Binding of Isaac and Enter the Gungeon, there are a lot of item combos you can find that make you pretty powerful, in a variety of ways.