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.