It sounds like you are just looking for a way to simplify database access. But what's the point if you can't find all level 3 accountants not within 3 years of retirement who live in Ohio that have not yet been to training class 256 in the last 18 months and have not had training class 214 in the last 12 months? Sounds silly? Databases can do that. Filesystems can't. I'd absolutely hate to see a filesystem implementation of that query -- why, because it would make one's brain explode. Databases involve more complex data structures than simple hierachies.

Consider effiency lost -- if you disagree, please justify the running time of the algorithm you would use to search a filesystem dump of a database.

Proc is one thing, but proc isn't trying to be a SQL database. They serve different ends.

If you want to write a filesystem driver to interact with a database, that might be interesting ... kind of Plan 9-ish.