Chances are your application serves multiple purposes. It supplies data to a mobile application, it might supply data to a node.js application, it could be a back-end only application and more. SOA (Service Oriented Architecture) is a necessary paradigm and pattern to build your applications in such a way to play well with others. APIs may be the ultimate part of the puzzle but designing your architecture in a service oriented way will help achieve building your API in a far quicker way.
This talk was generally a good overview of some SOA architectural concepts, nothing that I was not already familiar with but all valid information. The presentation was fairly heavy on code examples, which I would normally be opposed to but given that this was my first PHP conference I was actually looking forward to some PHP specific implementations of concepts. I agree with other attendees that there could have been more information describing the problems that are being solved, less for my self than for other team members in attendance. Not a bad presentation but not the most compelling session for this conference. I would probably attend another talk by Mike.