In this case, scraping content makes perfect sense for a search engine that wants to show previews or other useful content for search results. Not sure what the big deal is, aside from providing somewhat nonsensical fuel for people who really, really want to have a big finger-pointing "j'accuse!" moment with respect to Google.
I don't see how you can argue that Google's scraping adds value in cases like this. They literally grabbed the content off Wikipedia and put it in a box... right above the snippet from Wikipedia that appears in the #1 search result (which is Wikipedia).
Arguably if the source you're ganking content from is in the top 3 results, you might as well kill the scraped content box so that people can see more search results above the fold, since the content you scraped will be there anyway.
Of course, the boxes are good for Google, because they let them exert more control over visitors and traffic. Google puts enough of the source into the search results that the average visitor might never click through to Wikipedia.
It actually adds a lot of value, at least for me. If you notice it doesn't show up these cards for all searches, but only for direct questions which it understands and can answer with fair enough reliability. It relieves people from the hassle of going to webpages to find the answer to their question. Most of the times, that's the only thing they are looking for. Your concern about eating away traffic from Wikipedia is correct, but the big question is what matters more to people in general - going on to a website just for the sake of it, or quickly getting their answers? When I ask my phone, "How old is Barack Obama?", it fetches the same from wikipedia, produces a 'Card', and reads the answer out to me. That is enormous value.
That's not the sort of thing being discussed here, though. The example in the linked article is a search query that is literally the title of a Wikipedia page that is #1 in the results. You can find other examples for other queries. In these cases, Google adds zero value with the box but it is there anyway, depriving Wikipedia of traffic and user interaction.
It's surprising hard to explain why it's ok for google to do this, but not other sites. The best I can come up with is "their search engine, their rules". Doesn't sound very ethical.
For one you were already using the site in order to get to where you can see it. I don't think google is making more money by putting certain information at the top, but they might be taking away money from where they got it from. They are also citing where the information came from.
Maybe google could give the potential ad revenue back to the sources.
Because journalists have an incentive to attract readers, and it worked. The blog post made it to the front page of HN.
(I don't think I've ever written a news article about a tweet and likely would not, barring extreme examples such as @WhiteHouse tweeting that the president had resigned or somesuch.)
