IMHO there is absolutely nothing wrong with thinking of data in relational terms. After all, there is a clear isomorphism between a row which has columns, and an object which has data members. The one fundamental difference — which could be seen as a shortcoming of the relational paradigm — is that objects have behavior. And the definition of behavior is what really constitutes "type". Of course, the OO paradigm has its own difficulties. How do you join two vectors of objects? Or, How do you implement an object which, conceptually, is relationally multiple tables?

I know, some will say that these are solved problems. And that some systems, e.g. Oracle's PL/SQL, give RDBMS the OO that it needs. But these are extensions; they're non-fundamental.