I don't like your example image too much, but generally I would like grass (and generally vegetation) which fits to the style of the landscape. However I see no reason why this shouldn't be particles or objects.

I don't like your example image either. It's not clear anymore where exactly the earth ends and the grass starts.

For the dynamic landscape generator, it should already be possible to add a grass material on top of all earth chunks (if border does not work well, such a feature could be added easily). Alternatively, the map zoomer (ChunkOZoom) could do it on a fine scale.

Problem is: IF its supposed to look nice, the zoom shader would have to know about it. It would have to use different seem textures for grass-to-earth (roots) compared to grass-to-sky/tunnel (grass top).