Had we killed Saddam in a targeted strike, what would have changed?
The Bush administration hoped that it would make a big difference at the start of the war, and spent a lot of effort trying to "decapitate" the regime in hopes it would help, but I think in hindsight he was wrong on that.
Obviously, Saddam's capture has not seriously dampened the ambitions of those underlings who probably see themselves sitting on his throne. The Baathists of Syria have some ambitions in this area, too. The road between the Sunni Triangle and Syria is like the main highway of the insurgency.