Everything was ash. Whether that be the black flakes that blew across Ponyville on the stagnant wind, or the solid compound that framed the ponies in their final moment of life. Everything was cold and empty. Immortality had a price.
The truth of the matter is, Spike didn't realize that writing The Noble Dragon Code would get him worshipped as a god but, hey, whattcha gonna do? Them's the breaks.