I kind of disagree on Heat Blast being "spam" mostly because when you Hypercharge, you aren't just hitting Heat Blast, you are alternating between 3 buttons very quickly since you are expected to weave Gauss/Ricochet between Heat Blasts. I disagree with it being "clunky" I think the flow of MCH is really smooth, with the only problem being the Barrel Stabilizer/Wildfire thing, but I do agree that Wildfire itself does need a looking over.
Honestly, when it comes to jobs, pretty much all of them have had their complexity toned down, MCH is no exception, I firmly believe that any problems MCH has now are the result of how terrible it was in SB, which took the fairly engaging and dynamic style of HW MCH and made it unreasonably strict and rigid, with baffling decisions such as using flamethrower on a single target to slip into overheat, which was by far the worst latency problem MCH has ever faced, they basically fucked it up when streamlining the jobs in SB, I genuinely don't believe it was playtested properly, practically no one enjoyed playing it, MCH players were laughably low at this time, even when they buffed it hard, no one wanted to put up with it, the devs had to apologize for the absolute state of it and had to promise a rework to unfuck it. I played quite a bit of SB MCH and I firmly believe it was a failure in terms of design and execution. Bear in mind, this is coming from someone who absolutely adored HW Machinist.
ShB MCH by comparison is much simpler, but it takes MCH in a solid direction thematically, you play more like a master of machinery, but there were problems, like Wildfire feeling inconsequential with the rest of the kit, with it being 120s for a hit that won't even be as much as the very common drill if it crits or direct hits and even when using it with your hypercharge window, nothing really changes, you just perform your hypercharge loop as normal.
I actually enjoy the gameplay loop of MCH due to its high APM, taking a job that has fewer buttons but you have periods where you move much faster and more often than before, I enjoy the speed, even with complaints of latency, an obvious quick fix for hypercharge is giving you 5 charges of Heat Blast while changing little about it, since I actually like the resets on gauss and ricochet, my only real complaint is that Heat Blast feels like a very "meh" skill, again, blame SB MCH for this. I get that 1-2-3 can be seen as boring, but honestly, its hardly any worse than mashing Burst Shot and praying for Refulgent procs. MCH has to keep an eye on cooldown timers closely to ensure no overlap, which I do enjoy, I do think there could be a few more actions in there, still hoping for Edgars Chainsaw.
I do miss some thematic elements of the job, like reload, rend mind/dismantle, old hypercharge, I really liked MCH's old identity as a debuffer, could give a vulm to the enemy with old hypercharge and lower incoming damage by debuffing the enemy with rend mind/dismantle, as opposed to protecting the party with a party buff, making a "selfish ranged dps" was never gonna work because of the ranged tax on dps.
I do echo the "choice GCD" though, I really dislike having a single-target/aoe equivalent, demonstrated greatly with Samurai with Senei, it shares the same cost/recast with Guren, literally nothing about your rotation changes in the slightest, you simply push Guren for aoe, Senei for single-target, I found it to be a very poor parlor trick by the devs to make you think you are getting more skills than you actually are (as well as removing skills and giving them back later like Divine Seal -> Temperance)
Sadly, the battery gauge being a glorified DoT is a trend in the current design philosophy, they nixed almost all meaningful interactivity with the pets for SMN/SCH and even DRK's Living Shadow is just a fancy looking DoT, its less a problem with the job itself and more how the devs are aiming to remove any and all interactivity with pets/turrets.
I don't want to write out any large essays on the subject, but on the whole, I think ShB MCH is still a very fun and fast paced job and the rework for the most part has proved popular, though really, saying its an improvement over SB MCH isn't saying much, the bar was so low to begin with, but I think MCH has a very solid foundation to work on going forward assuming they look at what works and what doesn't for the job, I don't feel it needs any sort of rework, more that it gets some kinks ironed out. It isn't like 5.0 NIN or SMN, where their rotations were flat out broken at times, MCH is ultimately working as intended, so its unlikely we will see any big changes before the next expansion.