I don’t see much of this kind of disparate experiences with people talking about D&D3 and D&D4?
It looks to me as if 3e and 4e are designed to facilitate more conformity; they simply
have more rules, especially for more common situations, to match in the first place!
AD&D1 ended up not really laying down clear rules for so very much more than OD&D. The "major systems" in which uniformity might by any stretch be reckoned actually possible added up to very little next to WotC's games -- even if some (such as initiative and spell casting) had not been plagued with errata amounting simply to imponderables. Even the professed intent needs, I think, some context for understanding other than the anachronistic imposition of 3e or 4e values.
Is this change from extreme-variance in play experiences to more uniform play experiences a result of the edition of the game, or a result of our culture?
Both, I think quite clearly. For instance ...
Was this variance in experience with AD&D1 also present in OD&D and BD&D?
Yes! Gygax clearly and explicitly (considering statements not only in the DMG but in TSR/TD both before and after publication) meant for AD&D to produce
more uniform play experiences than had OD&D. He meant the new (Basic and Expert, projected Companion) D&D line to take over from the Original Collectors Edition (which was then discontinued) the role of tool-kit for free experimentation.
As it happened, though, most old hands moved on to AD&D (having started back in 1977 with the
Monster Manual). Most of the newcomers who remained actively involved for decades seem also to have made that move, if they even started with a Basic set at all. (Indeed, I suspect that most who prefer "Classic" today returned, or even came newly, to it after some time using the "Advanced" books.)
The two demographics seemed in my experience to tend to opposite responses to the new line from the self-proclaimed "final arbiter of fantasy role playing" -- who previously had proclaimed that conformity was absolutely
not to be desired, and never would be promoted so long as he had a say.
The old hands tended to treat the new books simply as compilations of D&D material, requiring no sudden 180-degree turn in approach. If they paid any great heed to the pomposity, it was to find it at best silly; to take it seriously was more likely to nurture resentment.
Newer (and especially younger) folks were more likely to take it as Holy Writ earnestly to follow. Moreover, whereas before there had been a selection pressure toward people who liked the mutability, now it was if anything in the other direction. The new and much bigger, more "mainstream", market was a different demographic.
Although AD&D was by then far from the only FRP game available, quite a few brand loyalists seemed to regard it as if it might as well be the only game in town.
I don’t see so many arguments about how OD&D and BD&D were played differently by different people and compared to the rules as written.
There's a vast variation not only how the games "were" but in how they
are played -- but it's not a big subject for argument. There are not a lot of arguments, either, about how AD&D
is played -- in the sense of "Someone says their experiences were A, and another person says their experiences were Z, and they get into a big argument over whose experiences were right with the game as written or more common among the general player population."
No, the argumentation of that sort usually has to do with an attempt to claim that some other game is "just like AD&D, only better". Few offering such rhetoric seem very familiar with Original; they seem largely to dismiss Basic+ as of little interest; and seem widely either to regard 2e as a "red-headed step child" or to conflate it with 1e.
But surely AD&D2 didn’t give a more uniform experience compared to AD&D1. Is this because AD&D2 seemed to be actually made to have highly varying experiences, what with all the supplements produced in its era?
The supplements were produced and consumed in a feedback loop reinforcing conformity to "by the book" rules, culminating in the
Players Option volumes. In other words, by picking and choosing among expansions you could get a wide variety in details that were
all "Official Rules". By the end of the decade, I understand that it was pretty common to be using the latest version of "everything". I don't see a huge difference between that and the situation that was repeated in 3e and expected from the start in 4e.
Quite apart from that, 2e not only had
clearer rules in the core books but also had
more rules for the sorts of things -- such as
non-weapon proficiencies -- that have continued to figure so prominently in WotC's games.
I think the clarity was a big deal. The style and organization of the books helped greatly, as did editing with an awareness of what had been unclear before.
Note that TSR solicited -- and received! -- a lot of suggestions as to how the Second Edition should be. From what I have seen, many of the "official" changes were in line with already common house rules.
Making the game into something that Mike really likes may mean making it something Becky really dislikes. That increases in likelihood the more that Mike was dissatisfied in the first place with what Becky liked.
Now, the Beckys drop out, and so the Mikes are a new majority. As the game gets even more to their taste, even fewer Beckys join in -- and so "everyone playing the game" is even more mostly Mikes.
From the commercial standpoint, the natural hope is that a base of Mikes is more profitable. That is not necessarily synonymous with more numerous, or any one of a number of other things that the Mikes might desire.