Seconded. I've been asking for this often (*) —grid under tokens makes much more sense to me.
It's useful as well to have building roofs and tops of trees on maps without grid lines over them, for meaning a higher height, different of the floor level.
(*) For instance, "Grid over *all* images & tiles in a map?" (<a href="http://community.roll20.net/discussion/1119/grid-over-all-images-tiles-in-a-map#Item_1" rel="nofollow">http://community.roll20.net/discussion/1119/grid-over-all-images-tiles-in-a-map#Item_1</a>)