The things that we buy (consume) and the openly (conspicuously) display are designed not just for our own enjoyment but also for the impression they will make on others.
This pattern may be seen in many aspects of funerals.
The size, shape, and material of the casket are important, not because we are concerned about whether the deceased will be comfortable in the grave, and certainly not because we are worried about how long the casket will last under the ground, bur simply because for the few minutes that it will be seen by those who attend the funeral it will serve as an indicator of wealth and social position.
Surely no one would claim that the deceased is more likely to be admitted top heaven in a metal casket than in a pine box.