OK, fine. I'll concede devs want more interactiveness. I have yet to see evidence that users want more interactiveness. I think that points to the arrogance of devs "who totally know better than the user".
This had traditionally happened through POST/GET requests and having all the logic server-side. Yes it's possible to build interaction without Javascript, but it's not a great effect. Imagine if you had to wait for a page load every time you voted on a post on reddit.
Now extend that to modern webapps. Take Google's Voice Memos demo[1]. It loads instantly. It supports any device. You can even add it to your homescreen and you won't be able to tell it from a native app. Everything about it just works. Why would a user not want such an experience?
Javascript interaction is the natural evolution of the web. If it wasn't JS it would have been something else. This growth has been driven by users, devs, and browser vendors alike. There's nothing "arrogant" about it.
Hi, that's me. The reason is, quite simply, because this is not a good user experience:
https://pbs.twimg.com/media/CmaP3JvUcAA8-5a.jpg:large
The open web is my platform of choice, and the technology is finally there. Progressive Web Apps[1] offer the features of native but are instantly-available, without downloading or installing. So yes, I very much want that as a developer.
https://developers.google.com/web/progressive-web-apps/