I don't see anything intrinsically wrong with using a web rendering engine as a presentation layer, but I don't like the bloat and know that at least some of that bloat comes from the fact that the UI layer is a web app written in JS. I'm also not a fan of JS.
Is there anything out there that allows you to pop open a web rendered window and control the DOM from outside from another language? Seems to me that this would let you do sophisticated HTML5 UIs maybe leveraging things like Bootstrap and Framework7 but without JavaScript and thus without the associated JS VM bloat.
If there isn't anything like this, someone should make it.