In most yinrih cultures, one honors the dead by making good use of their remains. Burying the body after death is a statement that the remains aren't worth using and the person they belonged to isn't worth remembering.
When willed by the deceased, burial is regarded as sacrilege in the Bright Way. It's often done by Partisans and Atheist Atavists as a rejection of Claravian teaching on the nature of the body (and the universe as a whole) as a deliberate work by an intelligent mind. Burial was also used in the past as a posthumous condemnation, as demonstrated with the corrupt overseer who founded the City of Eternal Noon.
The usual use for bones as architectural adornment is less costly than a human burial because the defleshed bones take up much less space than a coffin and headstone. Nevertheless, if cost is still a concern, one can elect to have their bones pulverized and incorporated into the brickwork of new lighthouses or other structures. This process is also the typical ultimate fate of bones displayed in a lighthouse once space runs out.