If the rovers have a robot arm with a brush at the end of it, would it have been that hard to figure out a way for a rover to brush dust off its solar cells with this, or a different, less-abrasive brush tool? I don't have a model of a rover in front of me, so I can't tell what the "reach" of its arm is, but maybe they could have added another "elbow" or something to allow the use of the arm for self-maintenance.

For example, if the rover tipped, it would land on the edge of one of the solar panels, as near as I can tell (I really wish I had a model in front of me.) Is its CG low enough that it would right itself from that point? Could it use its arm to push itself back up?