Google should be asking from a product perspective if they are providing the search results the user is most likely seeking.
I seriously doubt that most pinterest results are what users are seeking. As such, Google probably should consider changes to their algorithm to compensate (cat and mouse) for pinterest's gaming. That is assuming how pinterest does it is not against any google rules... because if it were against any rules, they should be slapped down hard.
When my searches result in mostly pinterest results, I give up more quickly. That means I spend less time using google, and that in theory means less money for google. Unfortunately, I do see other more regular user types operate their computers, and they are less or un-descriminating about the domain name listed under the image. So they'll head directly into the pinterest waste pond anyway.