I'm coming at this from the same perspective as gdilla. In the end, the mesh networks connect to the Internet, so why do they all need to operate in the same way? Each app will have its different requiremens. For instance, some will need to focus on extremely low power, some may need more emphasis on security. Why not let these apps drive their individual protocols, and then fly the end data or queries over the Internet?
From a security point of view, it's probably smart to assume that your network is accessible from the outside. But from a practical point of view, interoperability of INTRAnets of Things seems like something purist hackers want and not industry. If you are an enterprise, the data, the apps you create, and things, machines and sensors you hook up are proprietary. It's not a fair comparison to say Things should be like websites. It's more apt to say connected things are like resources in your private network.