As someone who is afforded the privilege of seeing many OSS when evaluating vendors, it strikes me that most OSS are designed by Engineers.
It seems to me that if a developer hits on a user interface (UI) that can perform the required function then that interface layout will do. After all, Engineers in the OSS industry tend to have too many other tasks in their to-do list to trial different UI layouts.
But that’s where UI designers come in. They have the responsibility to try many variants to see which will work best. It’s the difference between why Apple’s iPod outstripped the interface-challenged MP3 players that proceeded it.
In my years in the industry, I’ve only known of one OSS organisation that had a dedicated UI expert on staff. Do you know of any? Are you one? If so, I’d love to hear from them / you.
BTW. I have a theory that if a 7-8 year old can’t navigate most of your GUI then it needs more iterations. That’s not just a comment on the OSS industry, but everything that feeds into an OSS. That includes network equipment (death by protocol), service offerings (death by options / bundling), etc.