This isn't 100% true. The majority of that is the native shared library and binary resources. These could be hosted centrally and loaded from an APK. It isn't totally necessary to package them in an APK.
But in that case you're both drawing attention to the fact that your app is HTML5 (which thanks to Facebook is associated with a low quality experience) and also that the user has to download a separate library in order to run it. You'll likely get a significant portion of bad reviews solely motivated by this, just as with apps that require the user to download Adobe AIR separately.
In my case, I happen to be doing something completely different with AOSP. I'm not looking to build a webapp for the Play store. We are embedding AOSP on our own hardware.
You still have to download the library at some point, and the library has to end up in your app's private libs folder. Android doesn't do dependencies or inter-app shared libraries outside of those that are part of the platform.
Actually, it's just what I was looking for in this announcement from Google. We currently deploy our internal apps on phonegap, and I want the snappy and the APIs that Chrome offers over the stock webview.