IMO all this google shift is happening because of Anti trust case being investigated against google.
Logic is simple.
Once they declare that they are not search engine but they are knowledge engine or whatever.
They may get away with this Anti trust case. In that case they can argue that they are committed to show the different pieces of knowledge (read maps, videos, images, news, snippets etc) and they dont work like a search engine any more which merely shows list of websites related to the search query and link to those websites.
My 2 cents.
I remember Microsoft had argued in their own Anti trust case that IE in Windows OS is like car stereo provided in a car, Free of cost.
So basically google is doing the same thing creating some base for the arguments in court.