I've now gotten around to fully removing javascript from Epicyon. Previously it only had a few lines of javascript for the content warning button, dropdown menu and for moving the cursor to the end of some text, and that's now all been replaced by html.
It's easy to see why web systems become bloated with megabytes of javascript. A lot of programming involves web searches to look up how to do things and for web content such as a dropdown menu it's highly probable that the first example you'll encounter will be written in javascript. It's actually quite difficult to avoid ending up adding some amount of javascript. You have to be consciously not wanting to do that, rather than just going with what's easy.
Javascript isn't necessarily always bad, but it can create security problems and in a Tor browser it often involves the inconvenient user experience of having to fiddle with NoScript - which itself has a rather hostile interface - to allow it on particular sites that you trust.