In my experience, from working amongst marketeers, bit.ly is still used not because of its link-shortening abilities. It's used because of the analytics and insight it can provides.

Even on sites with comprehensive analytic packages integrated, bit.ly (and services like it) will be used because the people doing the "social media" work an the people responsible for the performance of the website online are sitting in different places and not talking to each other.

The result is this division of statistical data for each party to beat each other with.