Well, that's only five paragraphs but there's a lot of launchpoints in there. What do you think about Jack Vance'd Dying World, and its magic? What do you think about how it's influenced roleplaying games? What do you think about how it was adopted, and how it was changed over the years? What do you think about conceptions of magic between real-world practitioners, anthropologists/folklorists/storytellers, and gamers?
Having read Vance fairly recently, it strikes me how idiosyncratic and bizarre the "magic" system he picked was. It's a very odd approach, one that's completely at odds with virtually every take on magic in mythology, and almost more like super-science than "magic" as we know it.
The equivalent would be, I think, if say, D&D was created today, and the creators decided to model the "magic" system on Brandon Sanderson's
Mistborn series. It's a wildly idiosyncratic take, has no real connection to mythology, and in that case resembles superpowers more than "magic".
I don't really believe they particularly "thought it through", either. I think they just grabbed a system which was easy to implement and which they were fans of. Implementing something like a more Earthsea-esque take on magic would require a whole entire approach to rules-making which didn't even really exist at the time.
As for the influence on other RPGs and fantasy videogames and so on, I think it's been curiously limited. You can really split them into two groups - those directly emulating D&D, which often have Vancian systems, and those not emulating D&D, where close-to-none have Vancian systems. In videogames literally only D&D/Pathfinder games have Vancian systems, and not even all of those!
The vast majority of other games, tabletop top or video, go for spell-point-type systems, where spell-points can come back either extremely quickly or extremely slowly, and where pool depth varies greatly as well.
I think it's kind of weird and unhelpful that D&D has stuck to the system so tightly, and I also think that, if D&D did abandon Vancian magic, it would not meaningfully impair D&D's popularity, and would probably gradually and slightly increase it. People are obsessed with certain spells, but very few people actually care about the Vancian aspect. As 5E showed by moving hard away from "standard Vancian". Also D&D hasn't done a good job of emulating Vance, because D&D Wizards can cast dozens of spells, whereas Vance's ones often have like 1-6 spells memorized (and when they're used, they're gone, no more "using slots" on that spell). The only TTRPG I know which really does that is Worlds Without Number.
You can't just save up your points and only cast fireball. This is a good thing, and most spell point variant rules either end up being overtuned because the caster can always fire on full automatic (well, with a 5-minute work day but they're heavily incentivized to do that) - or they try to recreate this with additional limitations on high-level spells but those rules always seem kludgy.
I mean, this is really only true of a very specific set of spell point rules.
Those that:
A) Are intended to be retrofitted directly to an existing edition of D&D.
and also
B) Are designed around a very deep, long-rest replenished spell-point pool.
If you design an RPG to use spell-points or another related mechanism from the outside, you don't get these problems. If you design a retrofit spell-point system that doesn't use a very deep, long-rest pool, but say a more shallow pool that replenishes on shorter rests or continually, you don't get the the same issues.
So it's completely solvable. As countless other RPGs show.
It's also of note that, in the early days of D&D, one of the most successful and long-running D&D variants used spell points (and a number of other "before-their-time" rules, like non-casters having actual defined abilities in a way not really seen until 4E/5E, well or Earthdawn I guess), and I think it's very easy to envision a timeline where, perhaps, that became the dominant style of D&D, and this conversation wouldn't even be happening.