I dind't say I botheed to install the legal copy. I just keep it on the drawer and if I ever need to reninstall I get that. Or if there's some multiplayer content I need.
It's great that you have such a sense of morality and duty, but Slime Beast is right. Most people don't want to buy a game just so they can put in on their wall (other than collector's editions maybe). The reason why you bought the legal copy was not so that you could PLAY the game, but simply OWN it. Most people only care about PLAYING a game, than owning it.
I think you're admirable, and I can't judge Slimebeast since I engage in some pirating as well, but you definetly don't represent the majority of people. Who the fuck will want to buy a game to just decorate your room with? The only times I bought a legal copy was when I wanted to play Multiplayer, and it was already cheap (Rome: Total War), and because torrenting was too much of a hastle (Medieval II: Total War).