I think that a broader problem is that a lot of both games are not constrained to be physically accurate. Like, there are things lit up because it looks nice even though there's no in-game light source (like blue glowy caves or well-lit building interiors in Skyrim), or things lit up that don't cast light for performance reasons (like a bunch of neon signs in Fallout 4).

The devs tweaked it to look nice and dramatic, which wasn't always in line with what things would look like given an accurate rendering using the light sources that exist in-game.

Both games are notorious for having very bright nights outside. That bothers some people due to lack of realism, but making nights accurately dark, which a number of mods did, results in players stumbling around at night having a hard tine seeing anything, which annoys others.

Maybe one could just re-light the world and the mods that add areas -- there are mods that do basically relight the world already -- but I think that it'd be easier to start with a game that tries to use more-or-less accurate lighting from the get-go and then makes gameplay that works with that lighting.