I don't want an OS that "doesn't make me pick between iCloud or ~/Documents". That just means turning macOS into ChromeOS. An OS with just a search bar would break a ridiculous amount of uses, from shared computers or cloud drives where everyone knows to put the files in the right folder, but your colleagues have weird naming conventions, so you can't search by name, but if the files were side-by-side it would be common sense which one you want; to the dangers of ambiguity between cloud and local storage; to the reality that many use personal computers for work and would get fired if certain personal files/media showed up in a File Search for work documents. You imply that iOS-style file management is easier for average users, but at a previous workplace, there was a central Mac that had important text files with .odt extensions, all organised on the desktop, that opened in TextEdit since LibreOffice/OpenOffice was for some reason never installed. How would TextEdit show those files if all you had was the Mac OS X 10.8 Mountain Lion-esque TextEdit iCloud open box? The documents wouldn't show up, since it would only show TextEdit documents, i.e. rich text files (.rtd). If it makes sense to keep multiple types of files together, like text files and spreadsheets, you'd have to put them in a folder, not app-specific storage. But that sounds identical to what we have now. How would I open any random local text file in Google Docs? Wouldn't that be a huge privacy flaw, that Apple would never build into Safari anyway? You'd just end up with silos within each app, with no idea how to move things around, since I think the iOS metaphor is actually less intuitive than putting folders on your desktop with things inside them.

Everyone likes imagining better ways to manage files, but no one has been able to come up with one that's intuitive, not even Apple with iOS. The only reason they get away with it, is very few people actually ever interact with files on iOS. Instagram, Snapchat, Reminders, Clock, Safari don't involve documents, and for many people, that's what they use their phone for, period. Google Docs are in the app; how would they open in any other app anyway? As for iPad users, people might create something in ProCreate, and then export it. I don't think iPads are used as file storage devices, just as inputs to bring somewhere else.