Are relational databases overkill?

Relational databases are big, complex, doubly abstract systems that are used for persistence in even the simplest web app. Simple desktop apps don’t use them for persistence so why do simple web apps. With a large number of programmers doing OOP why are we not storing the objects transparently? I think I made a step in the right direction with REServe ( and the php version ) but it still makes to many compromises to the object model.

Where are the simple Object Databases. It should not be that hard to create a object database for dynamic languages and for it to be fast enough. Are developers just stuck in a relational rut or is there some other reason the object database offerings are few and far between?