I think dark mode was a harbinger of dumbed down UI. Instead of spending time on one good UI, designers and developers were forced to make 2 mediocre ones instead. Plus dark mode is easier if you remove all detail and depth from control elements.

I don’t think they built the dark mode version as an entirely new UI, it’s just some css and a class you toggle on the body, making it perfect would require some elbow grease but it’s not a complex feature really.

It's not a complex feature because most UIs have already been simplified and flattened into oblivion. If buttons and controls still had depth you might need two complete sets of assets. E.g. consider what implementing dark mode in iOS 6 might look like.

That's kind of my whole point. Dark mode features are a symptom of UIs that no longer communicate anything significant with color and shade so just changing color with CSS tweaks doesn't break them.

But designers and developed don't support one UI, or even two. They support anywhere between three (desktop, mobile, tablet) and effectively infinite (all resolutions between and around those + dark modes + apps which use the same data + all different browsers). UIs can't be very good one on platform without either making each platform's UI separate or sacrificing functionality on other platforms.

New GitHub looks alright on low resolutions, but looks kinda awful on big screens. This is the opposite problem old GitHub had.

There isn't a color scheme you can pick where you won't get users asking you for a dark-on-light vs light-on-dark version, whatever is the opposite of whatever color scheme you thought would be one-size-fits-all.

Though you seem to be suggesting that's somehow a bad thing and I'm not sure why. Dark mode is so popular that operating systems have even started supporting a native toggle.

I always look for the light mode button in this new hipster software.

Next thing I know, books will printed white-on-black.