The loafer tends to be a relatively casual dress shoe. Whereas black tends to lend formality to a pair of shoes. Consequently, black loafers just strike me as being self-contradictory. Like a "Hello Kitty" machine gun, or a rap version of the King James Bible. (Okay, perhaps not quite so glaring a contradiction as all that, but still...)
I recognize that exceptions exist, of course. For example, I've long thought that horsebit loafers look best in black. But what sartorial guideline doesn't have the odd exception or two?
Well, just my take on it. If the loafers were brown, I'd probably have no great objection to the. But in black... I wouldn't buy them. And the fact that you can get them for half price doesn't really change my opinion.