Google is trying to wrestle control away from the carriers after whoring out Android under their terms when it first came out. Obviously to get carriers interested in Android phones, Google had to ensure they gave power over feature set and update release to the carriers. This "control" caused a massive fragment in the market were phones today are still being sold with Android 2 to 3 versions behind the version of Android Google wants to ship.
While it may have ultimately made Android the top phone platform on the market today, it's cause a huge headache for Google to try and now release value added features like Play Music and Apps while supporting a wide assortment of random versions. Its also a nightmare platform to develop on unless you ignore everything before Android 4 and accept the limited scope of customers.
Not sure this is the best model for Ubuntu to follow because they don't even have the clout Google has that still struggles to get control back.
Carriers need to be told that they features of a phone is defined by the phone, if their networks can't support the feature then they don't get the premium top brands to sell to customers. For instance any carrier that does not support iPhone has seen significant decline in their customer base, this forces the carrier to support the features that Apple wants, not the other way around, to get back customers.
Also this goes completely against the openness of the Ubuntu platform as carriers are more interested in "locking down" rather then "opening up". Not sure open source and phone carriers are a good synergy, this product is doomed.
These are all great points, and I don't disagree with anything per se.
However, I think you are assuming that the future must be like the past. The phone market has undergone a series of significant changes over a period of decades, the past five (+) years with the rise of Apple and then Android coupled with the collapse of Blackberry and Nokia have only accelerated that.
I suspect that as the technology becomes both more powerful and ubiquitous the easier it becomes for a small competitor or open source project (Like the raspberry pi) to effect the entire market.
Competition is good.