Network executives expect tv shows to take off almost immidieately these days. With some much content and so much competition there is a great deal of pressure to get it right the first time. The number of shows that have been canceled after the first episode aired has increased exponetially in the last few years.
Network executives count mostly on ratings before making a new season of a show. They cannot afford to lose out on money based on the hope that something will happen that will boost their ratings. It has to be a proven success to continue receiving more and more seasons to come out.
Network executives have increasingly become more short-term oriented in their thinking. In the past, they would give low rated shows such as Cheers or The Office a chance to succeed if they believed in the quality of the program. Today, a show is often pulled after a few weeks, without allowing an audience to develop.
No, executives have always been short-term oriented and the perfect example is Freaks and Geeks. One of the most popular shows of all time, Freaks and Geeks was only given one season before being taken off the air. It is now a cult classic. Executives back then should have had the long-term goal in mind.