Or maybe you're just wrong?
I'm pretty sure it's possible to make something harder than "ignore it entirely and still pass." There's a wide gap between requiring 100% coin pickup or wiping a party, and the current version where you can ignore it entirely, pick up no coins, and still not have a single person die even when you don't outgear it.1. Its hard to make yojimbo's coins harder because of the mechanic of picking things up.
I have no understanding of how you can't tell the difference. It's impossible to fail this mechanic. Why even bother with it except as window dressing?
They added duty actions because of stuff like Vrill and the levitation thing that don't have anything to click on. It certainly helps with the brush because clicking on something with 8 other people on top of it is pretty hard, but that doesn't apply to the coins as you're spread out and they're huge, easy targets. Making you walk up to it and press the duty action button would change very little about the difficulty.2. I think they made duty action to remedy this, because you dont need to click on things, just hit the action over the object.
There's a reason why Rab is considered to have front loaded difficulty, after all.3. Yes, rab has the mechanic too, but even easier; there is nothing to interrupt it.
I was in one the other day that missed half of them. It makes no difference. That's the whole problem: there's no real reason to care a lot about it because failing it doesn't matter in the slightest.4. People already do the mechanic perfectly, not missing any coins in most of the instances I've seen; if they miss it, its one or two.