The want for a traditional burial of some form isn't for the departed - as you say they have no need of it, it's so the family can grieve and have some form of closure and often a place to go and visit.

This is going to entirely depend on the family and is a very personal thing and not rational, but the widespread of emotional response to loss is anything but rational.

Myself I don't care what happens to my cadaver when I'm gone, but my family can deal with it as they please to bring whatever peace they need.