And again, premium pricing is charged for basic service, and a new tier of ultra-premium pricing appears for just premium (but not ultra-premium) service.

Definitely noticed that trend. Quality of food offerings has also dropped dramatically to the point where I sometimes rather just fast

It does still offer access to power points though which can be hard in some airports

Over what time frame? Food in United clubs has improved immeasurably post-pandemic since I started flying with them in 2017. Still nothing like Virgin Atlantic quality though.

Meanwhile, the rest of the airport has improved. Free public wi-fi is commonplace (good riddance to Boingo hotspots) and power outlets are often easy to find. Plus, more people in the lounge means fewer people in the terminal.

In many cases it's not the same lounges. i.e. The international airlines still maintain their own 'exclusive' lounges, with whatever access policy. The public-access lounge is often not owned by an airline, making deals with card companies and smaller or budget airlines that in the past would not have offered any lounge.