Most every Linux distribution that I know of delivers minor system updates as separate packages. Why doesn't Google do this with Android?
The launcher, home, all of the individual Google service apps and even Motorola's own modifications could then be packaged separately (as an apk package I guess). They did this with the Facebook app, but I'm wondering why they don't do this with more of the apps (sync, bluetooth, etc).
I'm sure there is a good reason they don't do this since it would allow for faster bug fixes. Maybe it would be too much work (because manufacturers would probably have to maintain a separate repository for each phone model).
I know some stuff requires custom code by the manufacturer, but not all apps should require device specific code. The radio and kernel could require FCC approval, so I could see that not being included in the list, but there's got to be a lot more apps that could be updated this way.