Self-preservation isn't the only reason for Link to slice-and-dice the creatures of The Legend of Zelda: Skyward Sword. He can also harvest their oddly shaped innards to upgrade his gear. I've always wanted a sword with a spleen.
I'm a complete sucker for game systems that allow you to take treasure from monsters and modify your equipment. Sucker is almost too gentle a word, really. I obsess over finding everything I need to create the ultimate weapons and tools. Simply knowing they could be better than they are is enough to send me off into a monster slaughtering frenzy.