Having worked for Folio and NextPage, companies that have specialized in full-text indexing using custom search engines, I have an admitted knowledge liability with regard to relational databases. It never really made sense to have a relational database and our own search database coexisting in an application. But it never occurred to me that such a knowledge liability could be considered a benefit in terms of thinking about how applications should be designed.
J. Ambrose Little wrote an editorial about object-oriented design vs. data-oriented design that solidified some vague thoughts I've had about how one should go about building software. It has always seemed strange to me when people start application design based on what the database tables are going to be, but I thought that might be just due to my own ignorance.
In his article, Little's main point is that applications are frequently built by shoehorning the domain into a DataSet instead of building objects specific to the domain. In other words, many people are still not doing object-oriented design and programming, and gaining the benefits of domain-specific abstractions. One reason for this is that Microsoft tools make DataSets really easy. I've found that, while sometimes seeming like a second-class citizen, I'm able to use DataSet-like functionality like data binding in Windows Forms with my own custom objects with reasonably good results.
I'm sure I still need to become better acquainted with traditional database development, but hopefully my experience will allow a balanced view of how to design such systems.