What about the web components APIs are bad, and how could they be done differently given the reality of the existing platform?

The current state of the platform has even been a blocker to standards folk when they want to add a shiny new thing, thus the absurd bloat of the specs.

For one, they can stop pretending that JS and the DOM are two completely separate entities, and lock the two working groups in a basement until they figure out a sane way to do reactivity, natively, that actually works.