I do support your comment though that Dark Vision should be eliminated...
I said maybe.... thinking about it more makes me think that it shouldn't be eliminated - from a fantasy game. HARP SF, sure, go with hyperspectral and such, it is more of a science-based game.
Really, the only question you need to answer is this: Is it totally dark, yes or no? Not: How is it totally dark? Underground, heavy overcast night under quadruple canopied rain-forest, interior castle room with no light source, etc... None of that matters. Just: is it totally dark, yes or no? The only time it matters is if it is magical darkness, as I don't think the racial ability gives you the ability to see through magical darkness. (An option under the spell Night Vision, can give the ability to see in magical darkness, though.)
It is a simple, non-scientific, cause and effect, because those that made the spells in the first place weren't scientists, they were likely fairly primitive...not thinking in wavelengths and such. That is us putting our own technical spin on things because it is easier for
us to understand than: "Its magic, and that is just how it works." When: It
is magic, and that is just how it works.
The spell option works exactly the same way, only allows you to see a greater distance, and for a limited duration.
I truly think that is in a case of trying to over think it. To make it fit in to modern scientific ideology, when it is magic, ultimately unexplainable. So long as the in-game effects are consistent, there should not be much of a problem. That is part of the fun of magic, its mysteriousness. We don't know exactly how it does what it does, but it does it, and it can do some extremely amazing things in the "hands" of a skilled user. (In game, of course.)
*Exactly how far depends upon whether it is Greater or Lesser Darkvision.