If they are really that effective, is it going to help that much if we bomb half of the city apart? If he's that secure, how are we going to find him in an invasion? The idea of a surgical strike is to hit specific targets, not necessarily the leaders themselves, with quick and overwhelming force. Attacking the military command centers is just as, if not more, effective than the leadership itself. I don't know exactly how many people 4 brigades constitute, but I can be fairly sure that you can't put all of them into one place at a time. If Saddam's defence forces are as large and capable as you seem to imply, it would be much more effective to hit them quickly and precisely than to wear them down in a war of attrition.