To be fair, I am not sure just how common Darkvision was in previous editions. I think almost all my players in 3rd Edition were humans, and I never actually played 4th Edition (even though I do love those books).
However, there is no doubt that Darkvision has a firm places in D&D 5th Edition race design. In the Player’s Handbook, there are six races that feature Darkvision: Dwarf, Elf, Gnome, Half-Elf, Half-Orc, and Tiefling. Meanwhile, Halfling, Human, and Dragonborn do not have Darkvision.
If we expand this to all sources, there are 101 races and subraces with Darkvision. Only 59 races and subraces do not have Darkvision. I couldn’t be bothered to separate subraces out, but the picture is clear: Two thirds of all player races in Dungeons & Dragons have Darkvision.
This is a problem.
It’s especially a problem when two things happen:
One, the campaign features a menagerie of more or less silly proportions. There are cat people, and turtle people, and rabbit people, and elephant people, and so on. The more races are allowed, the more likely it is that the players will find something that has Darkvision. And since Darkvision is so useful, they’ll opt for a race with Darkvision, everything else being equal.
And two, Darkvision tends to be played – in my limited experience – as “you can see just fine in the dark”. This went so far that my character, a human Warlock without Devil’s Sight, and one other character without Darkvision, could not see anything at night, whereas everybody else had no problems seeing anything and everything, at all distances.
Characters without Darkvision are simply a lot less effective than those with, even when the rules are played straight.
If the DM takes liberties as above, it gets even worse. I am not a min-maxer, but if my character can’t do anything in combat other than fumble around and hope someone brings a light source close to the monsters, then we have a problem. (And why would the Darkvision characters bring light?)
The solution is pretty simple.
Remove Darkvision from all races and all classes. The exception would be campaigns that are set, for example, in the Underdark – and in that case, all players (and their enemies) get Darkvision. For some classes, Darkvision might be a limited use ability.
I do think this is a valuable change, even ignoring any character diparity issues. One of the pillars of Dungeons & Dragons is exploration, and “dungeons” are literally in the game’s title. If you effectively take away gloomy, dark, shadowy environment, you take away one of the cool aspects of the game. You lessen the game’s sense of wonder and mystery. You reduce the game’s fun.
Let the players worry about their last torch sputtering and going out. Let them fear what lurks in the dark. Have them worry about providing enough light to fight in. Or let them use darkness to their advantage.
And if you do want to hand-wave darkness, at least you do it on a level playing field. And no player will sit around on their thumbs while everybody else gets to have fun.