Document-based models are at least an order of magnitude easier to use than complex object frameworks. For proof of this we only need to look at the web. Only a few elite programmers are capable of grasping this sort of technology.
Time is money and life in business.
Furthermore, documents are the only cross-platform technology available, and that fact won't change any time soon. The skills shift has begun but it will take time for today's programmers to understand how any why to embrace a document-centric universe. It's a lifetime-duration process. In the course of just five years, HTML and its successor, XML, are everywhere. We are in the midst of a transition.