Database driven web designs may well look and feel the same to the end user but the way they are driven and the content delivered is fundamentally different. Instead of pages of static content that must each be maintained individually you have a repository (or database) of information that is retrieved by specially written software to display it in anyway you want. So why all the extra complication to get the same end result. if you have a 10 page website it probably is not worth it, but if you have a 20 page or more site then maintaining it can become onerous. Many of the pages are similar in look and feel but you are just presenting a different set of data.
For example, you may have a page layout for case studies of your successful projects. With a database driven design you need only layout the page once, write the code to populate the page with the information and then add each case study to the database. A properly written solution will provide a simple administrative interface to add those case studies.
This is just an simple example of what can be done with database driven web design. If you take a look at our Holiday Villas Web Designs you'll see a specific example of what can be done.
If you have a particular requirement to provide a bit more than static content that never changes to your potential customers then a database driven design may well be right for you.