Earlier quoted context omitted.
I don't work on open source but it could be: - Good design requires user interviews, which are less common in open source - The sorts of people who are most attracted to open source work are programmers, not designers - Open source software can get popular even with bad design; closed source software with bad design fails and shuts down
Designers have it really hard in free software because good design is about understanding the big picture, knowing what to leave out, have product vision to follow. That's tough to do in environment where goal is to make everyone happy and the biggest say have programmers who are developing the thing who are usually not interested in design, inexperienced in design or have their personal very specific product vision.
I even remember having this problem personally when trying to improve designs of webpages at my workplace. We had many of our technical users still using the command line for their mail, and even for browsing some webpages. Their whole workflow was stuck in the command line and they've been doing it that way for 20+ years. Trying to change things to improve the experience for others was like pulling teeth. They would retort the classic "Why change it? It works the way it is, no need to change it". Which to a degree I can understand. Some websites out there really do change their UI's for completely silly reasons and sometimes even lose functionality because of it.
At least this is one positive thing coming from AI driven development. People can actually make some pretty decent UI's without having to know as much about good UI design. AI can try to utilize the "best practice" standards and make a UI that often looks much better than most devs could make. There are some downsides of course, such as the fact that almost every new website nowadays looks the same, since Claude seems to have one style it always goes with. But maybe that tradeoff is okay.