Occasionally I'll hear people speculate that it's a waste that we bury dead people when they have so much usable protein. Leaving aside the cultural taboos, medical risks, and squick, is this an amount of meat worth trying to make better use of?

The world death rate is about 8 per 1000 people per year. (CIA Factbook) This is lower than you might expect because the population is increasing: average lifespan is not 125 years (1000/8). In a steady state the rate might be more like 14 per 1000 people, but let's stick with 8, describing our current world.

Most people die of diseases in a way that their bodies can be promptly recovered. If there are 50 pounds of edible meat on a body, then current deaths mean that every day human deaths could supply 0.001 pounds per living person. This is low-quality gamy meat because the average age of death among people is incredibly high for meat animals, so it might be equivalent to cheap $1/pound cuts of meat from conventional livestock. This means enacting worldwide cannibalism for humans would provide as much additional meat as spending one tenth of a cent per person on conventional low-end meat.

Not worth the social debate or the medical risk.