However, as you can see on this site it is a synonym of (favorite tags). (Which probably was not the case at the time when the set of default tags were selected.) And I guess most users know this feature under the name favorite tags rather than interesting tags.
As a result on most local metas this tag either remain unused of is used in entirely different meaning - obviously it was intended as a tag for questions about favorite-tags. You can check for yourself on the meta sites you frequent, or you can even browse a few local metas if you want to check that this is indeed the case.
For already existing sites, there is probably not much that can be done about this. (Perhaps developers or members of the SE team could be able to tell whether it is possible to change this also retroactively.)
But I would suggest that at least in the future when a new site is created, meta should be populated with (favorite-tags) in the selection of default tags.