Simple answer might be open source contributors don’t respect the work designers do as much as other environments and as a result don’t create communities that attract them.
Wouldn't a simpler explanation be that skilled professionals don't work on someone else's hobbies for free?
No, because the premise is open source projects which developers, skilled professionals, work on.
My real hypothesis, by the way, is that designers have been trained from early on not to do free work. The “work for exposure” meme captures this pathos.
You do understand that designers do have free will and a developer can't simply order one to work for free on someone else's hobby just because he could use specialized hep, don't you?
It seems you're entirely oblivious to the very nature of FLOSS software, where practically all projects are born as a single individual's hobby, and some of them happen to grow way past the single-developer stage. With that in mind, what exactly leads you to believe that designers have no free will of their own and simply spend their days working on someone else's hobby just because he could use the specialized help?
Case in point: my default reaction to see SaaS-style "pretty" page is to close the tab. I have my reasons to avoid SaaS as much as possible, so if my brain pattern-matches your site to a "generic SaaS" design, I almost immediately lose interest.
Am I a minority? Maybe. But then, I'm also org mode's target audience.
Think about Lowes vs West Elm. Both sell things for homeowners. But you can tell from their aesthetics what to expect. Lowes could copy the aesthetic of an Apple store, but it would feel very “off”.
There’s tons of open source projects with nice looking sites. It’s one of those HN blind spots
You didn’t survey anyone either did you?
Have you seen emacs? It ain’t pretty. But it’s effective and works for a certain type of person. This aesthetic fits the emacs aesthetic. If this site was too polished and pretty, people would expect a polished and pretty product.
It indicates it won’t be easy to use this product, and it works to attract the correct user. If it was beautiful, people would have different expectations for the tool. This design indicates it’ll require work to set up and understand.
In the same way this site would never work for a nice macOS app, a Panic site wouldn’t work for this tool.
I've seen "better designed" open source pages, but they tend to send the wrong message. When you see a mostly-well-designed open source page, your brain just feels like you're being tricked. You feel like someone's trying to charge you for something, or it just feels wrong.
Design is contextual, and what we think of as "well-designed" tends to be from a SaaS perspective, and that sends the wrong message. You see it and think "oh, this is a SaaS product," and your brain just feels weird.
This is true for all design. In markets, generic brands use a worse design to signal they're "cheaper," cereals for kids use cartoons, etc. The vibe needs to match the product, or else your brain sets off alarm bells.
Open Source projects use design to project what they value. Org mode for Emacs should feel like... a site for emacs. Simple, clear, no frills. Whereas a site like Prettier looks nicer, because that's the whole point.
(Also, separate "design" from "usability"... this site isn't pretty, but I can find everything I need super easily!)