The trend in software development tools and platforms for the past few years has been open-source -> provide for free -> charge the support services. I think it’s safe to say that no one expects Oracle to open-source ADF, but some steps could be taken to, at least, boost its popularity.
ADF has been on the market for several years but even though it has shown great potential and amazing capabilities, the number of developers familiar with this framework is very small. This is one of the major reasons a company would hesitate to use it.
Allowing deployment to a Web container like Apache Tomcat or Glassfish without requiring a licence could help make this tool more popular with developers and promote it to academic communities.
Oracle would have nothing to lose.
For large scale projects the obvious choice would be to keep using only Oracle licenced products to have guaranteed high quality support and services.
Small scale projects for which until now no one would even consider using Oracle products due to their cost, could combine the ADF framework with other free technologies. Oracle would profit by the further promotion and increased popularity of the framework and could also sell support and services to these smaller scale customers.
The full JDeveloper and ADFramework Pricing FAQ can be found here