Just because it's badly abused doesn't mean it's bad per se. Let's say you build your SOA: JSON API + Mobile App. At this point, if you plan to build a web app to browse your content, it's very hard to render pages server side without code duplication/collision with the API. If you go with the full js MVC approach you can reuse your api and just worry about the templating and event binding. Maybe this approach doesn't yet scale to the size of Twitter, but I hope the web moves towards fat clients optimization.