On the topic of flat design specifically, developers are likely just as culpable. Back when it was just starting to catch on, by my observation some of the quickest to adopt it were solo developers because it's way easier to build a passable looking app with flat UI since that doesn't require any design talent.
lunar_rover|1 day ago
Unless something like https://kde.org/announcements/plasma/5/5.12.0/spectacle-noti... is what you consider to be passable looking of course.
VorpalWay|22 hours ago
I'll take function over for every day. (I daily drive KDE, it works fine and doesn't get in my way. Most of the time I'm either in my editor or the terminal emulator anyway.)
maxloh|17 hours ago
The screenshot you posted is likely from KDE Plasma. The project don't have much funding to hire a UI/UX designer IMHO.