The thing is, a lot of websites don't need to be interactive, or only need to present interactivity to a minority of visitors. Consider Wikipedia, for example. Only a small percentage of people visiting the site are interested in editing anything. The rest shouldn't be burdened with massive quantities of extra downloads for a feature they don't need, want, or use.

Furthermore, you don't need a "modern web framework" to have an interactive site, and most of them seem to be pretty bloated.

The level of technology a site displays should be appropriate to what the site is trying to do. If your site is about services that you need an appointment for, then yes, there should be a booking setup on the site. If you're running a store, you should have a shopping cart. Add as much of an interactive layer as is necessary to do these things, and do them well, but no more than that.

Most of us just want pages to render quickly, stop tracking us unnecessarily, and stop choking our connections and stealing our electricity for stuff that isn't useful to us (or to anyone except depraved corporations).