Image style tokens don't show up in the media browser, and so you sort of have to guess at how to use them. I figured it out by studying the merged commit that added the functionality.
Personally, I feel overwhelmed looking at the ocean of metatags presented on the node edit page when the metatag module is installed.
How much more overwhelmed would a regular ol' user feel?
I created a small modules to hide the extra form elements from the metatag module: