But the suite of google apps aren't (maps, gmail, access to the market, etc). Google has tons of leverage.
I think the obvious solution here is to put in a simple skinning API and let the devs go nuts with it. Sense, TW, etc would just be apk's that skin the GUI elements. End users should be able to disable this if they wish.
Google could use its muscle to make this happen. Shame they won't. In the meantime, the released stats show a big move from android to iphone because people seem to prefer Apple's way of doing things. Heck, I had a phone with a published security vulnerability and it took almost 12 months to patch it. That's 100% unacceptable.