(My opinion - not suggesting this is why we did it)

There is a difference between what you need for a dictionary to *work* versus what makes it nicely readable.

For example, internally, to us, a user is just a number (you can see it on sys.user$). But that's not helpful or you - you want to see user *name*.

Same with objects, tablespaces, roles, etc etc... The "application" that is the Oracle data dictionary only needs to work with surrogate keys etc...but the "user" (ie, DBA's etc wanting to see the dictionary) want more useful information. So we have views to expose that data more cleanly.

And that of course (like any application) is useful when we want to change the underlying structures yet insulate the "outside world" from those changes. We just alter the view to present the same information but from the new structures. Its good practice for *your* applications as well