Evil, no, of course not. There's many reasons, including religious ones, why people choose not to donate their organs.
However, I would ask you this: What are you really going to do with your organs when you're dead? If you're not using them, I say, give em to someone who can. Being an organ donor doesn't mean they're going to let you die or anything if you get into a bad accident just so they can steal your kidney or something.
We have hookers with bathtubs full of ice who do that. (jk... maybe)