This, so much. There's a reasonable set of common JS usage patterns out there that really ought to be replaced with declarative statements in HTML and supported by browsers, so that doing things like dynamic forms, drag-and-drop areas, page transitions without reload, notification badges, etc. would not have to require running arbitrary code.

Intercooler.js provides a preview of what this could be like, but, of course, it's layered on top of javascript since that's the hammer we have to work with.