That one tileset is probably the worst pallete edit I've ever seen, and I have no idea why anyone thinks it's a good idea to use it. It's especially bad if you play it in a window where everything behind it is a bright colour.

I remember getting complaints for using the night version of Swamps in The Marshland of Evil. And that tileset isn't even that dark. I eventually switched it to the day version, because even the most marginal gains in playability are worth making changes for.

The point is, people like to be able to see things as clearly as possible.