It looks like a good idea to me to use something that you control as opposed to bit.ly, tinyurl and myriad others available, here's a quick list:
URL Shorteners: Which Shortening Service Should You Use?
The tracking is important to affiliates which includes getting the referrer information in addition to just tracking the number of clicks and reporting of course.
Is it worth investing in creating one's own url shortening service for personal use? Pros and cons, What's your take?