I watched Winston Groom on CSPAN yesterday and he pretty much said the same thing. Though, he was speaking from the point of view that after the fall of Vicksburg and retreating at Gettysburg, it may have been a wise idea to have some peace talks with Lincoln. He said we'd have gotten a "hell of a better deal" than we did. He spoke of his youth and riding across the South and still seeing the burnt chimneys and remnants of destruction that could have been avoided had Sherman not been unleashed.
He was doing a talk on his book : Vicksburg, 1863.