"go to Google News, or type a newsy topic like "Obama wins Nobel" into Google's search box. What do you get? Headlines and very brief teasers linking to news stories from news sites. If you click on them, you are taken to that news site, where you can read the story, which is surrounded by that site's ads. What, exactly, did Google steal in this scenario?"
What exactly did Google steal? Very exactly, Google steal "Headlines and very brief teasers". From the perspective of copyright law, yes, it can be classified as quoting, so they can't sue google, but those "headlines and teasers" do carry news value and in some cases took large amount of resources to produce. Now, Google took it and provided link as a payoff. Is that payoff adequate? Murdoch and many news producers don't think so.
Of course, teoretically you can use robots.txt. But in reality you can't, since your competition is also indexed, so you have to play by Google rules, even if you believe they didn't pay you enough for the value they are taking.