What RTS devs should do is make special objects on the battlefield that units can "merge" with. Like in Republic commando, you hover your reticle over a door, and you can tell one of your guys to open it, or blow it up. In an RTS, you could have special structures or natural junk (rocks or groups of trees), and when you have certain kinds of units selected, you can have them "merge" with the object and take cover from enemy fire. All the object would have to do is increase their defense stat or something by a large ratio (like x3 or something). Damn, I wish I could code. Now that I got this idea, I'm obsessed with it. Maybe one of the big mods could do it (since they have experienced/knowledgeable coders).