acquisitions and partnerships
Regarding the perfectioning of their search engine through their updates it just benefits big time them and just wipe out a chunk of "spammers". Because their algorithms are not perfect, it affects your site more or less each time.
I think they are not extremly agressive against the spammers in our industry, but I guess that do not represent enough importance for them to take care of that.
The users experience they claim is an easy excuse to do anything without taking responsabilities of what they really want to achieve and how they want to appear publicly.
Today it is still mysterious for any webmasters to know what Google really want from us, but they claim that they know what the users want!