Why have this work through a file system?
There are pro's and con's. If everything is a file you can talk to anything just by opening the file and call a handful of api's on it.
With an mmu comes memory mapped files, then access then just becomes memory accesses.
If everything isn't a file, then you have to open a different library before opening the thing and potentially calling functions similar to those on a file but just called something else.
mostly because CAOS was not ready in time.
I got the impression it wasn't just not ready in time, it wasn't being worked on at all.
http://www.thule.no/haynie/caos.html "CAOS was contracted out, for the most part, to a company that felt Unix was a better choice and didn't buy into my design. They became history when they started using their Sun development systems for other projects, not the Amiga higher level OS functions. "
The CAOS design wasn't great in places, it would have taken someone with real talent to knock it into shape. It's more likely to have ended up worse than what Metacomco delivered.