How is this better than an OS based on http, besides privacy and democracy? I'm very interested in this idea, I just don't know if "normal" people care enough about P2P for something like this to receive mainstream adoption.
Performance: With HTTP you have to constantly check if what you have cached is up to date because it could change. And a bunch of other little performance advantages.
Immutability: with HTTP you have to save things you care about because they might disappear/move in the future. With IPFS you could pretty much always rely on at least Google holding a copy of something in the long term.
Basically the idea is to remove the concept of local vs remote files at the OS level. So as a user of the OS the file browser and the web browser are the same application. They shouldn't even be able to tell if something is on their computer or not. This could be implemented on HTTP but only as a prototype.
Because of performance and reliability. Something built on top of something like IPFS makes the application generally faster and more stable. Gives you the benefit of being able to navigate things while being offline as well.
Imagine a social media, where if you're in a office and the connection to the general internet dies, all communicating within the office still works.