google has some very interesting systems problems to be solved that are almost entirely divorced from the fact that the monetary goal is serving ads, or even that the core goal is organising the world's information. the company is seriously attempting to push the boundaries of "how can we make large clusters of people, machines and networks more efficient and productive", and thompson's work on go is squarely in that realm.
(disclaimer: i work for google, but i was a fan of that aspect of the company long before i joined)