There is a lot of good experience presented in that article. But there is one place where they screwed up: It's easy to make apps for Android that scale up to tablet-sized screens. Failing to do that isn't Google's fault, and whinging about Google's preference to feature apps that run on tablets is unhelpful. Especially so since they previous, correctly, decided to build an Android design from scratch. If you do that right, it will run on tablets. Based on the tablet issue, their idea of building specifically for Android is still infected by a lot of iOS-itis.
You have a point here. A lot has been done in the Android framework to enable developers to build app that will scale up and down elegantly. However, keep in mind that there is more than supporting the physical form factor to it. To build for tablets vs phone is a different product mindset, with different goals and user experience. I don't expect people to open BillGuard every day on their tablet, rather to take their time on weekends to go deeper into the more advanced tools for example. Since the app is used differently, the UX has to be thought through specifically to take advantage of the specific platform you're building for.
That's a very complex issue. In some ways, Google's recent design trends and libraries, e.g. as in Inbox, do not take good advantage of large screens on the desktop or in tablets. I suspect Google aimed for a cross-platform UX first, before really tackling the screen real estate issue.
On the other hand, a tablet layout that "flattens" a UI hierarchy by displaying a list Fragment to the side of a display/edit Fragment is pretty simple to do. Material Design works just fine for this, too.
