Same could be same about good software design (as in programming), but we've found to design well written software before in a open source manner, I'm sure we could (if we focus on it) figure out something for UI/UX design as well that works in a open source context.
For example, style guides written and enforced by a small team can allow open contributions for the UI design.
I think it's mostly that not many have tried to figure out how to organize and actually run large-scale open source design work for UI/UX and that's why we haven't figured it out, I don't think it's "inherently" impossible.
And look at how these projects are organized. Most of the time it's pretty much top-down with a. It's why we have the term BDFL.
> good software design (as in programming)
That's the second problem. Most programmers probably know about about how good software design works, but have poor taste and prefer designs that aren't suitable for software that is to be used by non-programmers that want sane defaults that work and don't overwhelm them.
Just look at the theming debate. People in software developer forums are mad about it. Most users probably don't even know it exists. They just want settings and a UI that's simple enough for them to understand and allow for some basic settings.
So you would have to force volunteers to implement a design that they feel is bad. And you see how a lot of people react to it in the Gnome project where people leave because of it. But at the same time Gnome is a good example of how to do UI/UX for a big open source software project (even if you don't agree with their design decisions).
> And look at how these projects are organized. Most of the time it's pretty much top-down with a. It's why we have the term BDFL.
To make a more general point: top down leadership is not inherently bad. But in order for this to work well, people need to have the ability to enter and exit a project or polity at will.
(See eg how McDonald's doesn't let customers vote what to put on their menu, but customers are free to eat at a competitor or make their own food at home.
And compare that with North Korea also not letting citizens vote on their menu. But also taking steps to keep people from switching to a competing provider of government services, like South Korea. Similar also for the Berlin Wall.)
For example, style guides written and enforced by a small team can allow open contributions for the UI design.
I think it's mostly that not many have tried to figure out how to organize and actually run large-scale open source design work for UI/UX and that's why we haven't figured it out, I don't think it's "inherently" impossible.