Hi, this is a very interesting conversation, and I hope the most informative bits are reflected in https://www.mediawiki.org/wiki/Design
By the way, we are discussing the use of the term "Design" in the WMF product development process, as a stage involving not only visual/UX design but also architecture, performance, operations... Your feedback is welcomed.
https://www.mediawiki.org/wiki/WMF_product_development_process#Design
https://www.mediawiki.org/wiki/Topic:Srypura34nh1njr4