Because we can't transfer easily transfer files between devices remotely, we had to get used to do it via apps. And so we didn't developed good, local files browsers (esp. for media) and companies invested in the cloud UI mostly because they could sell the storage and sharing capabilities. That was all unnecessary but we're used to that now to a point where sharing files is weird.
As a power user happily syncthinging all my files between all my devices, I'm sad because files is the easiest thing to share, organize, transfer, etc. I wish iOS supported this kind apps (full storage access!) as we could avoid the many, crazy, Alps specific workarounds just to share some stupid files.
And don't confuse the file itself (say, a pirated movie), the metadata (IMDb IDs) and the apps UI (Kodi!). Files is what we have, we should share files and let anyone pick the browser/apl they like for viewing, organizing…)