Coders are the only ones who still should be interested in desktop UX, but even in that segment many just need a terminal window.
This also means that I heavily disagree with one of the points of the presenter. We should not use the next gen hardware to develop for the future Desktop. This is the most nonsensical thing I heard all day. We need to focus on the basics.
For example, we intentionally optimized Plasma 5 for low-powered devices (we used to have stacks of the Pinebook at dev sprints, essentially a RaspPi-class board in a laptop shell), shedding more than half the menory and compute requirements in just that generational advance.
We also have a good half-decade of QA focus behind us, including community-elected goals like a consistency campaign, much like what you asked for.
I'm confident Plasma 5 and 6 have iteratively gotten better on all four points.
It's certainly not perfect yet, and we have many areas to still improve about the product, some of them greatly. But we're certainly not enshittifying, and the momentum remains very high. Nearly all modern, popular new distros default to KDE (e.g. Bazzite, CachyOS, Asahi, Valve SteamOS) and our donation totals from low-paying individual donors - a decent proxy for user satisfaction - have multiplied. I've been around the commnunity for about 20 to 25 years and it's never been a more vibrant project than today.
Re the fantastic talk, thanks for the little KDE shout-out in the first two minutes!