I think this is a very broad question. Enterprise world is always under stress to complete the task onetime and using REST vs Session is more of architecture decision then a developer decision. If you use REST then there are many architecture challenges to resolve in a context of relatively small application. I believe that is one of the main reason why restful services are not used. However more and more companies absorbing HTML5 and jQuery and cloud model. May be next 5 year we will be there.