i can be an organ donor for ya, mint.
but honestly, i'm inclined to agree with you. my religion (with roots in hinduism, islam, buddhism and animism) doesn't say anything against it specifically, and in fact even encourages it. giving your body to help others after you have returned to your energy form is hella good kharma, i think? and it's helping others in general ya know, being subservient to your fellow man. seems like a good deal for me.
i can't understand why not someone would do this? besides maybe a religion thing that says that the body must be complete.