Their tombs were designed to resemble their abodes because it was felt the Ka would re-inhabit the corpse and need the sustenance of the food offerings for eternal life after death.

The entire foundation on the death practices revolved around this need,

As an interesting aside, this included assuming the descendants would screw it up and forget to leave food offerings so carving food containers were made in the tombs to magically provide nourishment when (not if) your children and grandchildren cheap you out!

Jammer