Like Mark Twain's death, the demise of the tank has been "greatly exaggerated." A weekend conversation with my World War II and Korea vet father spurs this column. Dad had seen a short video I shot in Iraq that featured my staff section racing down Baghdad's "Route Irish" in an unarmored SUV. Dad asked about the handling characteristics of SUVs and Humvees with "add-on" armor -- light vehicles that weren't designed to carry the extra weight. He then compared what I told him about steel plates and Kevlar panels to a Korean War "armor upgrade" to counter land mines: sandbags...