[quote=@Meta]
<Snipped quote by Threads of Fate>

Composting or burning would be more effective to that end.
[/quote]

Yes, but there's often a spiritualist component. There's also much more chance for pageantry with a burial, and there's a specific place to visit for their memory. Many find it distasteful to burn bodies, which leads to traditions such as burials when a species develops its cultures.