Grid over *all* images & tiles in a map?

I think that the Grid shouldn't be visible in the map for certain images, such as tiles above the floor level, descriptive portraits or images. If the Grid is placed above all things, no matter what, it may be difficult to know if trees, mountains, building roofs, etc, are actually at ground level or higher. While in most cases players intuitively know it, in other situations they are making questions about it. And overally speaking, to be able to make parts of the map Grid-less contributes to a better map visualization. Since we already have 3 layers for the map, maybe the third one could be Grid-less for the objects placed on it. Perhaps there is another better solution, though, like setting "preferences" for tokens/tiles (i.e., "Gridless? Yes/No"). Here is a small example that I did modifying the original screenshot from Roll20. The second image is the modified one, with grid-less sections for the walls. I could make a more compelling image, but this may be enough for making my point. Default Roll20 screenshot with Grid over all the map images:

Here is the modified image, featuring a sort of "selective Grid":

Here is another example that can make my point easier to see: Usual Roll20 Grid non-selective behavior (including the buidlings and roofs)

Here is how the same map-scene would look if there would be a way in Roll20 for placing tiles in the map whitout all them falling under the Grid: "Selective Grid", not including buildings nor roofs