Comment by panzi

Even Linux DEs have it less now than they used to, but there are renewed efforts to bring a better universal theming engine to KDE at least.

It's more difficult now than it was back then for KDE I guess, because with Qt Widgets, QML, and Plasma you basically have three times as much to support in a theme/theming engine. And then back in the day better KDE themes also provided themes for Gtk, so that Gtk apps integrated nicely. How many concurrent Gtk versions are now used that you would all have to support? And sometimes (especially non-Qt programs) take some colors from the theme, but not others, breaking everything when you want to customize your theme (you get e.g. black text on black background). So I appreciate the renewed effort, but I'm not holding my breath.