Nobody ever declared Sherman a saint. However, it is worth noting the reasoning behind this estimation of what it would take to defeat the south.
What drove the leading citizens of the South was the preservation of slavery. Various declarations of scession, Confederate state constitutions, and the statements of people like Edmund Ruffin were quite clear about it. These were ideologues who were willing to fight a Civil War to preserve their right to enslave black people.
Ideological wars such as this one are not won by the conquest of land. The enemy have to be personally defeated, which was Sherman's real point. The reasoning is identical to our goal of unconditional surrender by Nazi Germany.
It's worth noting, BTW, that almost all of those "murdered" women and childred you're crying about, surived the war and died of old age....