He didn't take them off the men who fought beside him to defend his ship, nor from enemies he had killed. Now that is a moral/alignment/personal choice but it seems icky to me. Though your referring to Asher in that statement is in reference to me you make it sound like I'm robbing the dead Roger, far from it.
First reason I'm taking them: In the story they carried pistols as you so vividly pointed out I'm better with pistols.
Second Reason: They fought beside me I want something to remember them by the best way to do that is to keep, carry and use them. Wolf would rather keep the handguns in his room or on his hip instead of seeing them get thrown in an evidence locker somewhere.
Plus so far in the game where have I had the opportunity to brawl or knife fight never. As far as using my pistols other then the mines and a few other times. When facing a heavier armed force with superior numbers, armor and assault rifles, its good to have as much firepower of your own. Survival 101
I'm still taking the pistols from Hack/Slash.