Comment 14 for bug 778540

Hiding immovables shows how the land will be usable when the player has harvested the resources (talking about trees and rocks here). I am sometimes interested in where players can build big buildings or buildings at all (e.g. for military influence), but this is currently impossible without removing the forest first. If instead I could hide the forest (and the build help would get updated), this was super useful.

Critters are rather small and do rarely disturb my view.

I am unsure whether immovables should be removed. As you mention, they might be used to create nice visual effects.