Google pagerank has become one of the most important factors, to determine how valuable is a web site. Many webmasters no longer care if your ranking well in SERP's or not, or even if you have high amount of daily traffic. All they care about is your web site pagerank and how much your charging per link.
Google pagerank is not only a tool to measure the importance of a web site, it has also become a symbol for almost all webmasters. The more pagerank your web site has, the more respect you get from other webmasters.