Unnecessary is key. Fancy animations, interaction reminders, cookie popups... they arent "necessary", but they make the experience _mostly_ better for both users (convenience), developers (easier development) AND management. Parent comment is unfortunately right, the web without JS will only be niche platforms designed for the noJS auidence
Animations and eyecandy don't require arbitrary code execution and should be handled by css, if at all. Almost all websites can be served as data, with the client free to render it how it chooses, which enables far more elegant and unified UIs than anything we have now.
Windows Phone 7 was a brilliant example of this. It was one last attempt by a large player to unite social media sites and messengers into one UI and interaction framework, and it was the most fluid, beautiful and pleasant OS I've used. Now that kind of interoperability would be borderline illegal. When you strip control away from devs about how their data is rendered, the results are generally more beautiful, not less.
I'm guessing that interaction reminders are those modals that appear when you go to close the tab, or prompt you to subscribe when scrolling down further. I would classify both as totally unnecessary and making the experience worse for users. They also do not require arbitrary code execution.
Cookie popups are a result of the ad-centered, panopticon-enabling web.
I know what I'm describing is far and above nojs. What I'm trying to get at is the motivation for disabling js, and what the web would look that if that principle were followed to it's logical conclusion.
