I agree that the carriers need to stop sticking their dirty fingers into Android, specifically you Verizon.
But.
You can't blame them for Sense, MOTOBLUR or TouchWiz (or that ugly-ass panels thing SE is doing). Those fall squarely on the manufacturer, same with locked bootloaders, et al. In all honestly, aside from MOTOBLUR, the manufacturer customizations add to Android. It makes it nice to look at and adds all sorts of features (my MT3G on stock 1.6 had no way to sync my Facebook contacts without extra apps, my Vibrant can do it out of the box) that regular people (IE: None of us in this thread) want, and that is what sells phones. And, at the end of the day, selling phones is all that matters.
I'm pretty sure Google could've laid down all sorts of restrictions on Android, and maybe they should've, but it's too late now.
Oh yes, and the Nexus One failed because it was more of the same old garbage that current carrier pricing is. Nexus Two (if it's even being made, which I doubt) will fail for the same reason.