Why are so much software developers working on open-source projects, but only so few designers?
A proper UI could increase the userbase a lot. I am quite sure that a lot of projects could benefit from good designers.

Welcome!

Unfortunately I have no answer to your question, but I do agree that """often""" (some people are very sensitive on this topic), open source software have poor GUI.

Yeah, i think it is really sad that so few designers work on open-source software. Sadly I am bad with UIs too, but there are so many projects that could benefit from a proper UI.

I think there are only a few designers involved at all. Probably because they do not work with open-source software as much as the average developer.

Indeed, this is also why so much of open source software is just very unfriendly to use. Also, UI/UX takes a lot of money/testing.
Blender is a great example of OSS with a good UI/UX community, they're really amping things up in 2.8

@RememberMe I never went to deep into Blender, but I agree with your statement. I know that many people aren't that much of a fan of Gimp's UI, but they have improved a lot, in my opinion.

Because many devs are so incompetent with regard to design and usability that they don't even realise that they could need a designer. Dunning-Kruger effect in action. And then they are even douchebags with their ignorance.

In commercial projects, they have their bosses tell them to get the designer on board while in OSS they have no bosses.

@andros705 UI design has as much to do with eye candy as software design with Joop.

@andros705 I mean just because there is "design" involved, that doesn't mean "bling-bling". The kind of overloaded stuff is rather typical for OSS because folks code the backend, which is fun, and then write a GUI wrapper for the CLI options, which isn't fun. The result is feature-oriented software that is hard to use because nobody has thought about work flows. No wonder because that development process is completely backwards.

Even if it isn't overloaded, there is still no thought about workflows and just leaving out arbitrary stuff, which gives feature-oriented software without features. Just think of Gnome 3.

@Fast-Nop Good UX is different for different people and unpaid contributors tend to make improvements that make the tool better for themselves, You don't get invited to opensource projects, you make the improvements you want and submit them to the maintainers (and if they don't want them you fork the project)

@ItsNotMyFault which makes things even worse because of the "too many cooks" aspect. Design doesn't work if everyone hacks in whatever detail he needs at the time, without any vision for the overall product. GIMP comes to mind as prime example for GUIs, and Git for CLIs.

@Fast-Nop I don't see how its worse, few opensource projects has people just hacking things in (PHP might be an exception), contributions that don't fit tend to be rejected, If you think some opensource project would benefit from "better" UX you are free to contribute. Just don't expect others to do your work for you.

Most opensource products have far superior UX (UX !== GUI) when compared to proprietary products, take vim for example, it is pretty close to perfect, all functionality you need can be accessed without moving your hands from the home row and there is no clutter, just the text you are working with)

@ItsNotMyFault Yeah, free to contribute. That argument, applied in the large, boils down to subsistency living, which wouldn't enable our current living standard.

And proprietary software has its own issues with different causes, but the question was about OSS. Pointing out weaknesses of OSS doesn't make CS good. Just like pointing out that it's bad to hit one's thumb with a hammer doesn't make it a good idea to slam one's head into a wall. ;-)

I'm a cs student/beginner WebDev &SDev with a thing for UI/UX and Linux. Maybe I need to start learning how to do some OSS work... I've been trying to find my niche.

Because the designers themself are not usually open source people.