Ability to degrade gracefully in the absence of JS
Still something that is missing from most web projects out there. Not cool. This is not only about surveillance, ads, trackers etc. – sometimes people are legitimately out and about (say on an archaeologist site) and they should be able to opt out of JS and the Web should be able to [minimally] serve them.
I’d like to see more frameworks allow something along those lines. Some of the app’s artifacts and functionality could be described with something akin to Rails / Phoenix templating language that varies its outputs depending on if the user’s browser has enabled JS.