I'd like to propose that a separate link to the Tag List page
is added to the media gallery.
XFMG comes with a tags block that can be displayed in the media sidebar. This allows members to see popular tags and also to search tags. The title of the block links to the Tag List page. If the block is disabled via the ACP, then users have no way of knowing that the Tag List page exists.
I'd suggest that a direct link to the Tag List page would solve this situation. The link could be placed in the Media navigation block and/or the Media sub-menu.