So I deleted my (shorter) long post to your prior post, to go with this one instead...The reason being, the only objection I have to any of these posts is the seeming implication that it is a problem with the game design as a whole.
In this post you are acknowledging that it's not a problem for everybody or the game design (which seems to contradict some of the things you said earlier, but I'm OK with that). Instead, it's a preference thing, and if you don't like everything having darkvision you are presenting an alternative.
To be exact - the problems I am discussing are these:
* it is too "easy" to create an all-darkvision party in 5th edition. Obviously it's always been as easy as an all-Dwarf team, but by this I mean that previously you needed to go further away from the archetypical human, halfling, dwarf, elf team into the exotic or monstrous (or duplicate) to achieve that, but 5e offers more character races than any previous edition, it is more "inclusive" of non-humans than arguably any previous edition (generally a good thing, mind you) and it simplifies vision into only darkvision or no darkvision. Note: this is far from a huge problem, since there are several solutions, including just asking your players to generate a party reliant on light if you want that to be a challenge (much like the OP).
While the problem isn't huge, the solution I present isn't huge or complex or intrusive either, which is why I feel it is proportionate: switch elves back to night vision.
* too many designers and players are seemingly ignorant of how light functions in dark environs. As a game it is obviously quite okay to just ignore this (much like so many other real-world issues are ignored or glossed over in D&D), but I feel better if people ignore the property of light to spread to huge distances
knowingly rather than because they don't know any better.
If for no other reason than to understand my reluctance to play a human rogue. In my view, you simply can't expect the DM to let you get away with carrying a light with you on your sneaking raids if it is utterly dark.
And you can't expect the monsters to helpfully light their caverns just for convenience, when you know how utterly foolish it would be to squander your advantage (=Darkvision) like that.
And no, "the others have darkvision too" argument does not hold water. In fact, that argument only reveals that you're STILL not fully cognizant of how remarkably far light will spread if it is utterly dark. You WILL be spotted if you have a light, which is very bad news, since it will make any intruder aware of the existence of a possible target/threat and thus go into "stealth mode", making it that much more difficult to spot them in time.
Obviously I don't think elves having darkvision is a problem, so I'm not likely to change it.
And that's okay. I certainly don't expect everybody to think about it as much as I do. It's "only a game" after all.
Just as long as you don't get upset if other players feel your lightning arrangements are too simplified, and don't start to design games with ridiculously short light-is-seen ranges
But for those that have an issue, which version of low-light vision do you prefer?
1) Double the range of vision for bright light/dim light
2) Dim light = bright light; darkness = darkness
They both have their moments of wonkiness in relation to darkvision, but they function quite a bit differently. The main reason I'm interested is that I still have an issue that so many nocturnal creatures don't have superior night vision. I may just give them darkvision since it's rarely going to matter that a hyena can see in the Underdark, for example.
Kind of both: I see no reason to reinvent the wheel - the d20 definition of night vision works well enough
Low-Light Vision
Characters with low-light vision have eyes that are so sensitive to light that they can see twice as far as normal in dim light.
Characters with low-light vision can see outdoors on a moonlit night as well as they can during the day.
http://www.d20srd.org/srd/specialAbilities.htm#lowLightVision
If I had to choose only one of your selections (say I couldn't use the 3rd ed definition for some reason), I would definitely go with your #2, since it is the simplest and quickest, and I'm assuming it still grants the most important benefit (the moonlight-in-forest benefit).