Sure, that makes sense, but not everybody leaves a will behind or lets anybody know about their wishes when they die, out of ignorance, sudden death, there are a lot of reasons why you may die and haven't told anyone what to do. Happens a lot with organ donors, for example.

In lieu of the deceased's will, the relatives need to make a decision. And, IMHO, this whole cannibalism thing is a lot harder to wrap your head around than having your loved one's organs harvested to save somebody else's life, for example.

Funerals are for the living, not the dead. I struggle to think of a good reason not to acquiesce to their wishes prior to dying, so as to make their grieving easier, given that yours will not matter at all then.