People disagree about the value of "clicks" as a measure of ad effectiveness.
Clicks were the great promise of online media. While traditional advertising could only be measured by sampling, surveys, and other guestimation methods, online advertising was sold as being completely accountable.
These days, there is robust debate about the value of clicks (responses) compared to more-traditional "branding" value. Both are values, ClickZ says.
Sometimes advertisers want to drive traffic; other times they want to build or reinforce brand reputation.