PySide for Android - build and use guide
qt-project.org
qt-project.org
In order to avoid having to learn Java, you use a third party framework that lets you author code in a more familiar language. In exchange, you have to bundle 16 MB of framework in your app and rewrite the whole Android skin in your new language.
Users hate dependencies. I wrote a game in the AIR for Android beta and half my reviews are people bitching about installing AIR.
If they know about them. In this case I believe everything necessary is bundled with the application (as is with Kivy mentioned above).
If OS makers could settle on a cross-platform and mature language that apps could be written in, these types of cross-compilation frameworks wouldn't be necessary. When I'm on my Windows Phone, how often do I hear developers say they don't have the resources to port to WP, or when I'm on my Nexus 4 hear developers say they don't have the resources to port anywhere but iOS?