However, I do have some reservations of a more 'ideological' nature when it comes to requiring javascript when it isn't strictly necessary.

I still believe one of the most powerful things about the web is the (relative) simplicity of the request/response server-side-rendering approach. There are so many ways in which a web page can be consumed (scraped, read-later-tools, etc.), within 'fair' boundaries of course. And this often falls apart because of client-side javascript.

This is fine when it concerns a web-app that is specifically made for browsers (where ideally there's also a public-facing API). But for most other things it should not be necessary, and I believe it harms the possibilities of the open web. And quite often I find that it deceases the usability in general (back-button breakage, etc.).

Of course, my ideal solution is both server- and client-side support, used appropriately, through something like React or PhantomJS.

...from sources which some people find uncomfortable to be blindly trusting. From a security perspective, it's a huge attack vector - the majority of browser exploits require JS to work. Even if it's sandboxed, there's also the annoyance aspect; scripts can consume CPU and do all sorts of irritating things like breaking the back button and seizure-inducing animations.

You don't need JavaScript for that.

    div {
      animation: seizure 16.6ms infinite alternate;
    }
    
    @keyframes seizure {
      0%   { background: black; }
      100% { background: white; }
    }