2E adventures were basically terrible. The good ones were in Dungeon magazine and late 2E near the end.
I don't have a ton of experience with published adventures in ANY edition. Most of the 2e games I was a part of were *very* homebrew.
I tried running a few when I DMed, but I agree with your assessment, so mostly went homebrew myself, and have continued ever since. I'll steal a short thing here and there, but largely do my own thing. Maybe that's why I don't "get" the reverence for "classic" modules. They hold zero nostalgia, and I don't have that "shared experience" that many players seem to have. I only look at the system and what it can or can't do for what I want to do.
2E excels at the settings and the various levers to build the game you want. They basically nerfed all the classes from 1E though and its where the wilder rogue Ranger basically turns up.
Yeah, having little understanding of the power differential, I allowed some players to import 1e characters into my 2e games, assuming the balance would be similar. That was a bit of a mistake, in hindsight.
One of the guys I had as a DM for years also smashed 1e and 2e together, to the extent that his "rulebook" was a big binder with bits photocopied from both games, including Dragon content. I didn't get why if we were supposedly playing the same game, why his take on how things should work would differ so wildly from what I had in my rulebooks. It seemed arbitrary at the time, but I understand it better now. I chafed against his play style quite a bit and didn't enjoy playing with him, but it was for a long time, "the only game in town" for me.
Still I can run it for modern players and they enjoy it a bit more than say 1E maybe BECMI/clones because you can cherry pick the rules to use. Kinda like 5E in a way but 2E carried it to more extremes. Want a high tech low magic D&D here you go, want a stone age high magic world well here you go. Want very powerful fighter well here you go etc.
Yes, there were a plethora of settings published for the game in those days. I owned the FR box, and a friend of mine owned a bunch of Greyhawk stuff. I got to look at most of the other ones out there. I had access to most of them, but none of them really interested me, other than stealing the bits I liked.
Again, perhaps why I didn't care *at all* when WotC altered the settings and lore during 4e - I had no attachment to it. I still don't. I get why people wouldn't like it, but at the same time, I never understood why you wouldn't just ignore the parts you didn't like. I'd been doing that basically forever.
There no established 2E is played this way unlike the other D&Ds where something at least is implied even if it differs a bit from how people actually play it (say 1E RAW vs how people used it).
I think the settings did the implying of playstyle to some extent. They all had a slightly different play agenda and expectations of what adventures would be about. Dark Sun certainly differed from baseline, as did Ravenloft, Kara Tur, and Spelljammer. Others, probably too, but I didn't play any Maztica, or Al Qadim, for example, even though I knew people that had the books (and I did read through them).
I took those as examples of how you might alter the game settings to achieve a specific result, and I cobbled things from all of them, but didn't like any of them as a whole.
3E also had this to a lesser extent there is the online hivemind and then how people actually played the game IRL.
Yeah, I saw this in action. Forum 3.x really exposed the weaknesses of the system, and took things to extremes. That said, I did notice the issues with it in actual play before that, but without the online discussion of *why* it was broken, with people who thought about it more than I did, and because we didn't take it to the same extremes, I couldn't really pin it down, but the issues were still there. Especially coming from 2e, which encouraged tweaking things to your liking. In 3.x, without really understanding what you were doing, tweaking could (and did) produce some very unexpected (and unpleasant) results for me. 2e handled this sort of tinkering much better IMO.
I probably could have continued with 3.x or PF, using an E6 or E10 paradigm, but ultimately there is just too much I didn't like about it, and now I understand both *what* and *why* -- so there's no going back. If I had to go back to a prior edition, I'd choose 2e and tinker with it, importing the newer ideas that I like.