Re trademarks: This isn't really a big deal. Mozilla strictly enforces the trademark for Firefox.
Google does it to enforce a minimum standard of quality. You're free to make an offbrand Android phone with your own apps and link it to the Amazon appstore or whatever.
The CDD appears to apply mostly to device manufacturers. It (1) specifies minimum system requirements and (2) requires that modifications to the OS don't break the API 3rd party applications use.
For 1, Hobbyists are still free to port Android to random unsupported devices such as the HP Touchpad; companies just aren't free to market devices that fall below minimum system requirements as Android devices.
For 2, if the API is broken, applications from the Android market probably won't work properly anyway.
Both of these sound entirely reasonable. Have I missed something?
Google does it to enforce a minimum standard of quality. You're free to make an offbrand Android phone with your own apps and link it to the Amazon appstore or whatever.