If you take his comments about overlaying text, for example, he's offering tips on how to keep overlaid text readable while also looking gorgeous. This is something that combines both usability with visual appeal.
I'd also argue that _people_ aren't a bunch of automatons who use computer interfaces simply to accomplish tasks. A "gorgeous" UI can make an otherwise mundane task (e.g., looking up which recipes to cook) into something fun and enjoyable.
I wish I could upvote this comment more. On a front-end client client for a US CBP command and control system, I had to design and implement both a day and night mode. The operators loved the night mode so much they ran it during the day too.. they called it sexy mode. It was the first time I saw how excited and fun they were having because they just felt cool using the system. The experience had a huge impact on me.
A UI that's entirely functional without being flashy or visually attractive still accomplishes its mission (e.g. space shuttle control panels). A UI that's beautiful to look at but can't be understood is of little value.
I think reasonable people can agree that interfaces should be usable and beautiful. I think it is then also reasonable that someone would want to have a focused discussion on just one part of that.