I don't know about a good thing. Many people enjoy the contemporary play style and it's not my place to say they should enjoy the one I like instead.
But for me the main issue is the mechanics of 5E don't work very well dungeon crawling, even as they manage to preempt the areas where exploration mechanics slot in best. Second, one is faced with changed player expectations. Lastly, while both of these could theoretically be changed, and presumably someone has the time and mental energy to play through complex exploration and complex combat, older adventures will still require redesign, because the means of handling these things in older simpler rulesets are different.
At a certain point I think it's better to either play an adventure in the system it's designed for or take its core ideas and rewrite it oneself for the system one is using.
I also fully accept that some people can or believe they can make these changes on the fly because of their experience at running games, but I'll say after decades of running D&D and some reasonable successes as an adventure designer, I haven't personally managed it in a way that's satisfying to me or my players, and I don't think I'm alone in that.
I don't know if I can really pull this off, I tried running a string of old Dungeon adventures in a 3.5 game and it went mostly well. But when I tried to run White Plume Mountain in 4e, it was pretty much a disaster; none of the fights were particularly challenging despite my best efforts, and 4e really didn't support exploration the same way 1e did, as 1e relied more on player skill than PC abilities- most PC's didn't
have exploration abilities. So you poke and prod and carefully examine things, and maybe the DM asks for an ability check here and there, but ultimately, it came down to the decisions, you, the player made.
In modern games we have clearly defined skills to notice things and gather information, and you might get a character who has a Feat like Observant or Dungeon Delver that really trivializes ever needing to carry around a 11' pole (if you know, you know). No one has to carry around torches or a bullseye lantern and have to worry about how much light they're bringing- even if you don't have light or dancing lights at will, the existence of continual flame means that someone is selling everburning torches, which, not actually being hot, could be hung on a belt loop or something for permanent hands-free light.
You could try and houserule the stuffing out of the modern game to bring back that old school feel, but at that point, you'd be better off just playing the old game, lol.
(I'm not bringing up Darkvision as a problem, as it has obvious disadvantages for exploration, and in some ways is worse than the old infravision. I'm not one of those people who misses low-light vision, because it was just as trivial to have light sources in 3e, and it was always a mess when you had some people who could see 20' and others who can see 40' with the same light source).
But I have all these old great adventures laying around, and I can't stand most new adventures. Not much I can point to, just, they just don't do it for me. So I'm stuck making my own or mining the past.
Now, the definition of insanity being apt here, I know this probably won't work out very well, but after spending a year and a half exploring a megadungeon where a good 75% of the time I had no idea what I was doing and there were simply no explanations for WTF was even going on, and the rest of the time was being savagely beat up by deadly encounters, I feel I can't do any worse, lol.