Google probably doesn't care about the quality of it's search that much anymore.

They've secured their position with all of the Android search toolbars in the world. And the "google it" verb. And YouTube's dominance.

Google's search results could be near-unusable and their business would still be secure, the only realistic threats to Google at this point are:

– Government regulation, break up.

– Apple releasing a very shiny search engine with a cool name and nice UI.