It's worth remembering that in many cases where genocide is occurring on an ethnic or ethnoreligious basis, what happens to the bodies is often part of the dehumanisation process - particularly where targeting a religion, the dead are deprived of the cultural burial rites. Mass burial or burning of bodies is not a greater respect to the dead, it's usually a case of seeking efficiency of space or disease prevention.
In the case of Gaza, the abandonment, exhumation, and seizure of bodies is a less efficient but particularly visible means of depriving burial rites.
Rarely does dehumanisation of a people cease at their death.