I think the seeming indifference and lack of outrage to crime of both Wheeler and Sherman can be attributing to the moral numbness and wearing effect of a long war. Wheeler did not give orders to his men to dig the eyeballs out of living men and Sherman did not give orders to his men to rape women.
The may be something in what you say, but I don't see the two men as morally equivalent. Sherman's troops were absolutely out of control, and he didn't act to stop it. He and his troops burned and robbed a path across Georgia and South Carolina. His troops hung people to make them tell where their valuables were hidden, his troops did rape, they burned houses, they left children without food, they fired cannon at civilian houses under Sherman's orders to do so (Atlanta), they stole an estimated 1200 watches in Columbia alone (Simms). Wheeler's men were not saints but they were not that bad.
I am reminded of Sherman's testimony in 1873 about Columbia that I recently posted on another thread:
Q. -- You testified, a little while ago, that it was very likely they [Sherman's own men] might burn Columbia, and you permitted them, or your officers did -- permitted them to go about the town?
A. -- I could have had them stay in the ranks, but I would not have done it, under the circumstances, to save Columbia.
Q. -- Although you knew they were likely to burn Columbia, you would not restrain them to their ranks, even to save it?
A. -- No, Sir. I would not have done such harshness to my soldiers to save the whole town. They were men, and I was not going to treat them like slaves. ...
It was too harsh to control his men by withholding from them the pleasure of robbing and burning the city? Then he tries to blame the city for its own destruction.