Agreed with you on the Monks - most of the Monks I've seen in pick-up groups are barely capable of even performing an FoB legally, let alone well. And for obvious reasons, it's quite rare for me to see anyone else perform a Ranger attack, so I don't have a good base for comparison there.
I'm probably also overestimating my skill a bit - it's been a couple years aside from that time I tried to pass the valkyrie's slide-on-the-shield skill test by dual-wielding (at which I failed miserably).
There's also the fact that I'm comparing my specific builds, which specifically use a token that boosts ranged hit but not melee hit, so I don't get the full benefit from the ranged token. I'm also comparing a neck token from the "neck tokens matter" era to a token from 2016, so maybe I shouldn't be surprised that this token matters as much as it does.
As you noted, the problem is that the 4th level Ranger card gives you basically nothing to work with. And a rare item isn't really the place to fix balance issues, so trying to somehow nerf melee with it by making ranged more appealing is never going to work either.
What I *personally* would want to see is some sort of rare-level version of Charm of Shadow Shot, because the biggest (non-balance-related) bummer about playing Ranged to me is only getting to slide one puck, but I realize that will never happen for at least five different reasons.
After thinking about it for way too long, I think the biggest problem is that it's too easy to stack +hit in melee, negating the supposed downside of the more erratic slides. Who cares how well you can slide if you hit on a 4? Obviously, that genie's been out of the bottle forever so there's nothing that can be done about it now, unfortunately. In my mind, the Ranger *should* be choosing between one super-reliable ranged attack or two less-reliable melee attacks, but due to the way the game has been designed, that didn't pan out.
If it was up to me, I'd probably make the neck +4 ranged / +2 melee (double the hits = half the bonus to each, right?), but I admit I'm probably biased.