Google is taking Cognitive Dissonance to a new level:
It's okay for them to scrape every single site, download its content and images, and cache it on their servers, and run their AD platform on top of it. but that's not enough, they would still like to impose their rules and punish people who do the same thing.
I'll concede that there's probably a middleground that's kinga gray, but are you really going to defend bona fide scraper sites? Like ones that simply grab all the text off some other site and repost it, adding no value? Google is obviously adding value by providing snippets from Wikipedia.
You can tell google not to download your site with your robots.txt file.
Also google can impose whatever rules they fancy, because it's their own site. Do you have a website? If I find some that you govern it with some rule that I don't like, should I rage on forums about it? Should you care if I rage about it?