Internet sites generate revenue by charging directly for items (Amazon), subscription fees (Wall Street Journal, premium versions of services) or advertising. Until recently, the New York Times had a mixed revenue strategy -- current news was supported by advertising and they charged a subscription fee for opinion columns and archived articles. They have now dropped their subscription service in favor of advertising.
Times executives may have felt ad revenue would be greater than subscription revenue, but, even if that were not the case, there is a compelling reason to make information free. If access to information is restricted in any way, people will be less likely to refer to it. For example, I would not have linked to a New York Times article on this blog because students would not be able to read the article without paying a subscription fee. By charging a fee, the New York Times had removed itself from the Internet "conversation."
Doug Kaye of the Conversations Network pointed this out some time ago. The New York Times should have listened to his talk on "value of free."
Or, the Times could have read the Internet business classic The Cluetrain Manifesto, which states
A powerful global conversation has begun. Through the Internet, people are discovering and inventing new ways to share relevant knowledge with blinding speed. As a direct result, markets are getting smarter—and getting smarter faster than most companies.People also "pay" for information by registering on a site. Does having to register stop you from entering sites or using services?
These markets are conversations.