I think routes can be irrelevant. Imagine you include a functionality to share some “data” directly with the other users of the system, think g+ or something. The actual route to the “data” can be omitted, when there is an in-app notification system.
Besides that, in my opinion routes are overrated. And it’s a good move for MDG to not make them a standard package. In my corporate app I have exactly one use case for a route (sending email notifications) and I simply parse the URL and make the app behave accordingly. That’s it.
Using the “back” button would make the user leave the app, in my case. Well, fine. He will do it once, maybe. A lot of users are burned by using the “back” button and loosing all their form content. I don’t think many people expect a fully functional “back”.
In my case reopening the app will restore the latest state, since I store a good part of that state on the server side.