This article in XT3 explains why Catholics don't scatter their ashes. Father Brian puts emphasis on the dignity of the body. But to me, the best reason is Having my ashes scattered means that there's no place where those who remain behind me can come and pray for me, while burying them in a sacred place is continuous with the Christian tradition of showing our remains the deep respect our body deserves as a Temple of the Holy Spirit which one day will rise again.
