I think there's a wisdom in our sadness about this and in our intuition that what happens to his actual body *does* matter. It is a deeply human impulse - and certainly part of ancient traditions, including Christian funeral and burial traditions -- to treat the human body after death with respect and care. These rituals can be the expression of tenderness, one last act of taking care of a child, or a parent, or a friend.
Beyond that, for Michael in particular, as troubled or ambivalent as his relationship with his own body may have been, his body was his instrument, and its hard to think of anyone more in touch with his body and the physical world than Michael on stage. Think of all the threads about Michael's smile, his eyes, his dance moves, his voice, his mannerisms - to the extent we know him, or feel we do, it's not as a disembodied soul. He was so fully alive, and it hurts to think about committing his body to the earth.