I've found a workaround, albeit still unnecessary and the wish change of function still stands;
If you detach the terrain editing window from its docked area in the editor UI, and/or re-attach it to an attachment point while having the terrain selected will remove the hue and you can freely swap between the terrain tools without the hue until you deselect the terrain. Then it'll return to getting purple any time you target it, until you detach the terrain mode window again.
