...and platform fragmentation, perhaps?
I understand "Fragmentation" is a cute and trendy word to use but TFA is actually right in saying that it's not the SDK that is the problem, but graphic resources and the fact that tablets are a much different beast than a simple phone, and the workflows (aka use cases, aka user stories) cannot be the same on a phone and a tablet. Applications designed for small devices miserably fail to be attractive on tablets because they aren't re-worked for them. However, most of the work in doing this is actually about re-thinking the interface and how it is going to be used. If you code your app correctly, there is no difficulty in re-using your components for one device size or another.
And back to fragmentation, the real headaches come from working around bugs in older version of Android that still need to be supported. That, my friend, is the real pain. And testing because you need to basically test each Android version.