You need to take into account that not everyone wants RNG in their jobs. Some like the fact they can plan everything out, some like the RNG nature, this is why there should be a spectrum of jobs that fill all those niches of playstyle. The same is true for positionals, not everyone likes a positional heavy job, but that doesn't mean one shouldn't exist (RIP Monk).

If we also go back to what you call 'positive RNG' (from the first post), you seem to be looking too much from one side. I've already mentioned RNG on DRG combos for Fang and Claw/Wheeling Thrust, so I'll talk about the others.

Thundercloud. Now, I'm not a BLM main by any stretch of the imagination, but I imagine, if everything lines up and you get your Thundercloud proc/Fire 3 procs when you want, it feels good, but, what if you don't get them. You are relying on them for movement, and they just won't proc. That is going to feel bad and I'm pretty sure that's why Sharpcast is as it is now, for more leeway. Yes, Swift/Triplecast exist, no you cannot rely on having them available when you need them.

AoE Dots on Bard, the only reason it felt good was because it proced a lot, I don't see you mentioning single target, which is a dead giveaway.

Dark Knight, technically, you didn't need Dark Dance, to activate Reprisal and reset Low Blow, Dark Dance just increased the chances of it happening.

Having a boss randomly buster you without warning is bad design, you will need some sort of tell that it is going to happen, then, assuming there is no guarantee that the boss is going to use a certain number of these busters, your performance in combat is entirely dependant on what the boss does and everything is out of your hands. Plus, it is just pressing a button to counter, i would hardly consider this as 'positive rng' and would actually consider this negative, however, I might be misunderstanding exactly what the intent was.

I also know you liked the old MCH combos with the ammo system, of which, the ammo is there to specifically negate the RNG.

There is something very common in all of these points, and that is the fact you have some sort of control over the RNG, whether it is DoTing more enemies for more proc chances, increasing the chance via Dark Dance, getting those guaranteed combos via ammo and, I suspect, having Flourish on Dancer helps in the burst phase as you can guarantee you have the required procs available, or the mass accumulation of Chakra on Monk during Brotherhood etc.

The RNG feels good when it works for us, when it activates, however, you also have to take into consideration when it doesn't. Those periods of time where you don't have something to help manipulate the RNG in your favour. Those times your 12 on Dancer never procs, or you never get a feather. Those times you want just that one Repertoire proc for a full power Pitch Perfect just before you go into Mage's Ballard, never getting the Verfire/Verstone procs on RDM, never generating a chakra stack between Bootshines on Monk etc. We have all had those bad patches, but they are the things that stick out more rather than the times it benefits us.

And, to comment on guaranteed procs in burst windows, if you were to take them, it would feel even worse. As you have already mentioned, not getting Refulgent Arrow back in SB in the burst felt really bad and the same can be said for other cases as well.

Again, to reiterate, I have no issue with jobs being RNG based but to claim RNG is the thing every job needs so that encounters can feel fun again, you are mistaken.