It makes the conceptual model of the OS more complex. Filesystems with basic permissions are easy to understand becuse of the forced structure. IMO, ACLs are

It makes the conceptual model of the OS more complex. Filesystems with basic permissions are easy to understand becuse of the forced structure. IMO, ACLs are a bad idea for the same reason, they make it harder to see what is going on while not solving a problem I actually have. I guess they do solve problems that some people have so that makes them more attractive if you are one of those people but IMO there must be better ways to solve those problems. Personally, I'd like to see version control and file compression integrated in my filesystem. I do not want my operating system to be distributed or rely on network access. I also think a separation between administrative access to the full system and views of applications may be a good idea. It seems to me that the ideal OS would heavily restrict the file and network access of applications and there would be a separate administrative domain with full access but limited complexity. The operating system then manages the sharing of needed data between applications and network access that the user allows. I think having the system parse a standard configuration file format for applications would make sense in this model, but that configuration file can still just be text. Also having a sub-user permissions structure similar to the overall system users seems like a good idea to me. Many applications that users run are hostile and dealing with that requires major changes vs current desktop operating systems. Database vs. filesystem is a minor issue in comparison and personally I don't see the appeal of using a database.