Anyway the tropiness or lack thereof of torches in fantasy was a bit tangential to my main points, but if tropiness is the measure, they can't be that well bested by Darkvision/Light Cantrip analogues, even in 2025, surely!
I think they can, actually.
Like if I sat down to introduce D&D with friends whose fantasy awareness is around that of the average person, they'd probably kind of expect or feel at home with something like torches and lanterns, but I'd bet they wouldn't see Darkvision coming.
I agree - but that's because it rarely comes up in things like Critical Role or BG3 or even discussions of D&D, but there's a reason it rarely comes up - its very existence means there's no point in playing weird lighting games, so D&D isn't a game about lighting, particularly. It's a bit of paradox or w/e but there it is.
That said, people would absolutely riot if you just outright removed it in a new edition of D&D, and that includes a lot of the tens of millions of people new to D&D with 5E.
Well let me ask you this way: with this in mind, in terms of gameplay enjoyment and general verisimilitude, how important are the mechanics of Darkvision/Light cantrips to you, versus the alternative of just saying or leaving unstated but assuming the fact that in this dungeon/location you can basically see at least 60 feet no problem?
For my money, you just need an explanation for why the PCs can see and how far. You don't necessarily need detail mechanics if you're running a gamist game like D&D, as opposed to a more simulationist one. Hell even in 1E/2E, the actual nature and precise mechanism of action of infravision was inconsistent and seemingly intentionally vague (outside of optional sources which defined it in contradictory ways).
I do think you need to know how it's happening, because that can matter. But I don't think trying to make it a resource to be tracked is very interesting, nor do I think precision mechanics re: darkness/shade/"dim illumination" (lol god help us)/semi-light/full light and so on are particularly useful or engaging. Humans generally have an idea how light works, and really it's like, are they so hard to see Disadvantage should apply or no?
Now, one thing that does matter is that players are clever, so if light sources work in different ways, that will come up as they explore and solve puzzles. I personally propose we go the opposite way with D&D to Shadowdark and the like (not that those aren't cool, but they're distinct and very good at what they do), and actually increase the availability of lighting to PCs, at least laterally - i.e. more options. I also think D&D's default rules should include better equipment ideas generally (they're pretty bleh in 5E, possibly the worst edition equipment-wise), because even if those don't interact with mechanics, players will come up with ways to use them. And that should include more actual-fantasy options.