Because someone needs to help him find some proper clothes.
Look at him. In Japan promoting Man Of Steel. You know when you see those old timey ads from the early 1960s and the homemaker wife and kids wait for the worker husband to come home with his lunchbox? That's where Henry Cavill found his outfit. How else can you explain this manila envelope shirt and these flood pants?
I'm not saying he needs to be Zachary Quinto. But you can't tell me, even if you're the most hardcore Henry Cavill, that this isn't killing your boner.