Honestly, they don't even look that great. Lots of sites could be using lots of modern browser features to be fairly innovative from a visual design and user experience standpoint, but it's mostly just really inefficient (and inaccessible, with no compat fallbacks) implementations of the same old shit.
> bring back the 1999 frame side bar. what was wrong with that?
That's funny. Back in the day, every Real web developer learned that frames are Evil and must be abolished, because they are breaking the back button and now the poor user can't provide a link to the view he sees, because the state of all the frames isn't encoded in the URL.
Then web2.0 happened and all the Cool web devs knew it's the time to start abusing ajax, use modal dialogs, break the back button, and turn simple websites serving text and images into complex stateful web apps and in doing so, ensure that people don't have nice URLs that encode the view they see, for linking.
Everyone thought it was silly when I did that for my site (minimal css, no js, static pages with hugo). But yea I agree, that's the right future for the web and design.
