There are plenty of arguments for why a newspaper or other traditional media outlet might decide to implement a paywall -- including a need for revenue to supplement declining print advertising, or a desire to form a stronger bond with its readers. But do paywalls automatically mean that you get better journalism? In other words, does a free and ad-supported model mean that the journalism you get is of lower quality, because of the "hamster wheel" effect?
While establishing a paywall does not create quality online journalism, it is more likely that ad-supported journalists are going to be measured by different metrics than those working for paywall-supported sites, and those metrics will likely include things like raw page views. The obvious point to be made here, though, is that for a paywall site to be successful, the quality of content must be high enough to justify the "entrance fee" - a high threshold to overcome. Things like general reputation of the publication's brand contribute a lot to this. For most online journalism, especially new sites, the ad-supported model will continue to be the best route.