Comments (I've only read half this thread, some of this may have been covered):
1) I love 5E, but it fumbled on a couple of things IMHO, and giving most monsters and most PC classes darkvision is one of them. It ends up that having darkvision is the default condition, and not having it is a rare disadvantage that some races suffer from. This is regrettable design.
2) I've homebrewed my races, and most don't have darkvision anymore. (Among a few changes I made.)
3) I think that the type of game you want to play should inform how frequent darkvision should or can be in your game, if you're inclined to homebrew. For example, i my game, darkvision is only useful every once in a while, because most encounters occur during daytime while the adventurers are on the move. If they manage to find a suitable place to sleep in, they won't be disturbed, and they usually avoid travelling by night (which is wise). If all my game sessions occurred in dark dungeons, or during nightime under moonless skies, then darkvision would become a central ability and the lack thereof would become very significant. So my decision to homebrew races that mostly don't have darkvision, results in the rare dark-dungeon encounters having a special feel to them.
4) In most dark environments, PCs light torches and they manage well with that. Having had darkvision would not have changed much in many circumstances.
5) Out of 4 PCs, one has darkvision. So most of the group doesn't have it, but the one that does, well his PC feels special for having it. I feel that having reversed the default condition of almost everyone having darkvision, where the one player whose PC doesnt have it feels lousy, to a new default condition where almost no one has it, is a success.