Good point. But shinigami is equivelent to the grim reaper in the cultural aspect. And there is Halloween or the day of the death in spanish cultures.
There are figures in all cultures that death is associated with and is accepted as part of life. I guess that is why they opted for the english translation of shinigami to be "soul reaper" because "death god" is not culturally known to the american or english speaking community (kids mostly).