That is the whole point though. It's not providing value to the creators of the data you're getting from Google. If you get your answer from Knowledge Graph, Google scraped that data from a website to give it to you, but didn't compensate that website for it, because you never went to the website and gave them ad revenue. Google kept all the ad revenue, because you stayed on their site.
In the past, Google created value for website owners by both directing traffic towards them, and sharing ad revenue with them. Now it's doing neither.
Directing traffic to a website doesn't always deliver increased value to a website. If I can find a restaurant's hours or phone number without clicking through to the (very possibly terrible) restaurant website and decide to have dinner there, that's a win for both me and the restaurant.
It's true not all websites depend on ad revenue, however, there are other problems with Google's Knowledge Graph: Others can tamper with it. There are numerous stories about malicious edits to Google's Places data to redirect calls from legitimate businesses, or mark businesses that are open as permanently closed.
While a business can control the information on it's website, it can't control the information on Google's, and often that is not to consumers' benefit.
They generally do compensate web sites. For example, when I ask for today's weather, it comes from weather.com and if I ask for the exchange rate for Canadian dollars, it comes from Morningstar. Both of those companies have a deal with Google to provide that information.
In the past, Google created value for website owners by both directing traffic towards them, and sharing ad revenue with them. Now it's doing neither.