attributes are a sticky issue and I haven't seen any clear consensus come out of discussions.
Personally I think it's valuable to have the metadata available - for instance there's code in the content management system to automatically generate forms, do revision inserts, map widgets to types (to serve as defaults) or attributes (to override the default), etc. The CMS UI is painful but the use of attributes isn't, though it would be nice to be able to describe attributes at a high level rather than painfully define them once in Oracle PL/SQL then Postgres PL/pgSQL.
Bottom line, then, is that the metadata has been used by aD in the past to provide for automatic content management of arbitrary content types and that we should make more use of metadata and work harder to support rapid development.
However the CMS carries its own attributes and other baggage due to its history as a standalone product but that's another issue.
So in my world I'd ditch the attributes values table, multiple valued columns (though we might be able to map those into Oracle and PG arrays in the type table since both offer some support), automatic initialization of attributes by the object creation routine (SQL's "default" works quite well for real columns in real tables), etc. I'd view the attributes mechanism as a provider of metadata in order to speed development, rather than a mechanism to implement a true object-attribute system.
As you can see from the thread here, there are those in the community who really like the full object-attribute model. My view is by no means a consensus view.
