Google does require certain things in order for it to get the Google branding. Currently this seems to be limited to including the core Google applications, but if google deems the rise of handset-specific frontends to be an issue perhaps they could expand the license requirements?

I, for one, don't see the proliferation of Motoblur/SamsungSense/HTC-Whatever to be a negative thing. It is an additional factor that consumers can use to differentiate between phones. One reason I own a DroidX is the great hardware, but another reason is I think the moto skin adds a lot in certain areas (it's calendar widget, for example).

In other words: let the market decide.