I've read that is easier for inexperienced people to fight from built up positions, which a city can probably be viewed as. The people of Misrata had the misfortune of not having anyplace to run to and the ironic good fortune of not having anyplace to run to. But they did have the heart. So maybe it is too much to ask the rebels in the east not to run like rabbits if they can; even if they do have the heart, they don't have the engineering capability to build fortifications in the open desert. They've had some time though and who knows what capabilities that time will give them.