The point is not that carrier or manufacturer customizations should be abandoned entirely (we know how much those guys hate standardization), it's that some of them are so poor that they actually detract from the Android experience. Going forward, it's entirely in Google's best interest to nix the pernicious effects of these contaminant devices and software builds. The average smartphone buyer is, ironically enough, quickly becoming a less savvy and geeky individual and he (or she) is not going to tolerate an inconsistent delivery on the promise contained in the word "Android."
My brother has an Android based phone on Sprint. Don't ask me which one. I can't keep up with the model numbers. I recommended he install Angry Birds for his son to play. After twenty minutes of searching the Google Marketplace we both gave up in frustration. We could not find Angry Birds. Later I realised that he needed Android 2.2 to run Angry Birds. The Marketplace app was smart enough to only show him apps compatible with his OS version. He had Android 1.6 and no way to upgrade. Or perhaps I should say he had no idea how to upgrade his phone OS. Well .... not true. He could buy a new phone and sign up for another 2 year contract.