Yes, and in some cases that's what makes it work well: different subsystems were designed to best handle different things, rather than trying to shoehorn everything into a single unified mechanic that maybe doesn't always do the best job.
I agree they have a worldview--as you say, its why you can run the same campaign with GURPS and Hero and get a pretty different play experience--but I'm not sold that's actually a support of theme.
I think you are misunderstanding me: what I'm saying is other way around. Better = modern.
Modern [X] is better than Old [X], because if it wasn't just strictly better [X], it'd be [Y] (maybe related to or inspired by [X], but still something else)
It's kind of like "Cogito, ergo sum": it wasn't meant as "oooh I'm so smart and thinking, and those who don't think are just NPCs", it was meant that cognition is, in itself, evidence of one's existence.
So like "modern = better" is "being strictly unambiguously better is a requirement (rather than the result) to be called a modernization, rather than reinvention (which produces something that is subject to taste)"
The problems arise when what is better for some people isn't better for others.
Your two Black Lotus pictures are a good example. The newer one's text is more streamlined, sure, but the older one's text is easier to read and understand.
Wilderness play, in OD&D and early AD&D, is structured fairly similarly to dungeon-crawling (map-and-key framing and resolution of movement) but with a different resource clock. I don't think it's all that well designed. I also think it's secondary to dungeon-crawling.
Even within the dungeon play mode, there were design elements that appear pointlessly ad-hoc. Once he'd gone to the D20 for attacks and saving throws, why are there random D6 or percentile resolution scattered about? Its not probabilities; you can get a pretty close resolution to either of those with a D20 most of the time. It comes across as "we needed something to be able to resolve this, so we pulled something out and wrote it down." And this is even true with systems presumably there was some time to think about such as thief skills.
None of this actually suggests thinking through the play-cycle of the game at hand in any at all rigorous way to me.
I don't think differences of dice rolled speak to issues with the play cycle. They can be connected to a lack of integrated systems (eg how does a thief moving silently relate to the surprise rules?). I don't think these clunky resolution systems detract from the focus of the game, though.
Then within a discussion of tabletop games, such a definition is useless, it describes nothing. Time has no relation to quality, or even substance of the mechanics -- in every era, there were wildly different game systems (and interpretations of the same game systems).
The very question in the thread title to me reads as being completely time-based, and could be synonymously rewritten as "what do you think of as newer ttrpg mechanics".
This has nothing to do with whether those newer ttrpg mechanics are better, worse, or equal in comparison with what came before.
That may be a result of PBtA engine being a victim of " New Hotness Syndrome" (despite not actually being all that new by now). It is IMO somewhat trendy to use.
We're talking about whether or not someone is designing with intent, or aimlessly.
Here you appear to be explicitly stating that it is impossible to have a valid intention other than to have mechanics tied to the overt support of a single clear theme. That Steve Jackson designs aimlessly and without intent, because his game lacks an adequate theme.
At a baseline and speaking broadly, I don't think it's controversial or requires much effort to identify that the intent of GURPS is to allow for the simulation a variety of reasonably grounded worlds. To allow players to engage in a variety of settings and styles with a consistent underlying framework.
I'm not sure what you mean by "style". But your first sentence in the second quote seems to identify the theme/goal of GURPS. It expresses a certain way of thinking about the world, and how action within the world produces results.
Your point of view. Plenty of games use 5e as a base even if it isn't really appropriate. Call it, "Popularity = $$$ Syndrome" if you like. I don't mind.
I've been on record as saying when viewed in a modern light that the OD&D design was sloppy as can be, and I'm not going to say otherwise just because some people love it.
I can't agree here; oD&D is primitive, not sloppy. Gygax and Arneson were working out things as they went and it shows. (It's also unclear). You need to wait for AD&D before the subsystems multiplied and the design got sloppy.