Being evil has its merits. And no, IGN is not just talking about the joy you can get from the wacky combat options. Sure you can kill somebody by firing teddy bears into their face, beat wild dogs to death with bats, or pickpocket chumps and leave grenades in place of their wallets. They are talking about being lazy, evil, sneaky...and getting rewarded for it. When they started up their recent play session with Fallout 3, their goal was to make as much money as possible as quickly as possible to get the best weapons out there. With that target in mind, one can't deal with pesky little things like morals.
The trouble is that it's sometimes tough to differentiate between good and evil in Fallout 3. Killing bad people like raiders or bounty hunters isn't considered evil per se. You're ridding the world of evil, so you're doing good. Apparently all human life is not sacred in this world.