Even if you disagree with the ability to track outbound clicks, ping would be good as if it becomes the main way of tracking clicks you'd be able to stop tracking by turning it off. When people do tracking by rewriting links server-side, on the other hand, you don't have an easy out.

I don't see this as a special case at all - a substantial proportion of link shortener usage, for example, is not for link shortening, but because most of them offer analytics.