I completely agree with the article, and this is the way I have implemented tracking within my WP RSS Aggregator plugin. Another good example is Easy Digital Downloads, in that plugin the author offers a discount on other add-ons if the user enables tracking.

On a related note, it would also be useful to know what data the WordPress software and related services such as Gravatar are sending back. I'm also of the opinion that there is not enough data being provided to plugin developers, which what motivates many developers to install tracking systems. As developers it is very useful for us to know which versions are in use for example. Before there used to be the version pie chart on the Stats page of a plugin, but it is no longer being displayed.