Google is not really an embedded developer, that is not whom they should be compared to. And if they were compared to embedded developers, they haven't done that bad, they have released their hardware specific drivers and even attempted to get them upstreamed.
But, they should actually be compared to a new distribution with a radically different approach to system design than other distributions. So, in this sense, if they do not upstream, they should be held accountable just like any other distribution. After all, Ubuntu got their share of complaints for this same reason not too long ago. And, at this, google has failed, they built new kernel infrastructure without community involvement and they expect this infrastructure to be used in newer roll outs. This is not a case of simply dumping support for a low volume device.
Being a large and a high profile company may not be a very strong reason to expect them to lead. But, since their "distribution" is high profile, and they are attempting to lead with this distribution, it surely seems justifiable to expect them to upstream the infrastructure required by this distribution or receive flack for not doing so.