What in one circumstance looks like respect can from another perspective look absurd. Personally, I believe the Tibetans have the best system. Bodies are carried up the mountains to be fed to the vultures. What could be more sacred than to be turned into vulture shit that rains down as fertilizer for all the life of ones land. The problem, of course with that in our culture would be that the pesticides in our bodies would probably cause vultures to go extinct and we would need more vultures not less.
I just don't see why this problem is so hard to grasp. A body is sacred when it can afford to be, and not when whatever notion of sacred you have if extended, causes harm to the living. The cost of respect can't be such that it does damage to the living. People are willing to make great sacrifices to honor the dead but somewhere there is a line that shouldn't be crossed.