While I'll agree that TK Monk was the job's peak, it was also the only time Greased Lightning was an actual mechanic, rather than merely a wind-up cost incurred once per continuous fight with a partial compensation likewise once per (continuous span of) fight. In T9 and a couple Extremes (Leviathan, etc.) that challenge was at least interesting, but it took all of a Tornado Kick bug giving it 30% more damage than was intended, old Riddle of Wind, and a less absurd CD on Perfect Balance for it to actually be a resource that offered the job additional agency.
Without that context, honestly Blitz's little rotational adjustments made possible offers more nuance than Greased Lightning itself ever did. That's not to say that Blitz is great, only that forming job identity solely as a penalty/constraint, rather than anything leverageable or even anything sufficiently compensated for, is rarely a good idea. More so even than positionals, Greased Lightning required appropriate surroundings to feel like a real job mechanic (whereby you might time a speed-drop in such a way as not to waste [de]buff uptime, or knowing that there's raidbuffs enough to compensate, or because you really do need the burst then and there more than you need total damage, etc.).
It still ticks me off that they didn't go deeper into the elemental and mini-burst-heavy route of late Stormblood, though. Small issues aside in terms of polish and some skills being left lackluster for the time (The Forbidden Chakra, especially), it was such a good direction.
I'd rather they had double down on the stance-based Riddles, actually made the stances themselves worthwhile and/or replaced filler-APM The Forbidden Chakra with a couple stance-dependent skills each with additional effects and able to spend 1-7 Chakra per cast instead of the fixed 5 with no bankability (or a single button, but the action depends on the number of Chakra spent).
Of course, would I still take a (more varied) Blitz system atop that? Sure. I want my Phantom Kick, Suplexes, Flint Kick, and Phantom Rush all (rather than good animations going to waste, replaced with level). I likewise wouldn't have minded seeing a take on the Dark and Light Chakra concept, especially as that seems about the only way Elixir Field would ever make any sense.