@mattl In my opinion it usually doesn't happen for similar reasons to why most FLOSS projects don't do user experience research.
Maintainers haven't experienced examples of it from other projects: thus don't grasp that it's possible, or understand its benefits, or what makes some efforts better than others
Contributors don't know how to design it well or how long it will take, or, yes, production skills
Survivorship bias: existing contributors didn't engage via video, so, don't perceive need