As opposed to cannibalism which is a taboo against eating one's own species, "sennibalism" (as defined in a slim few sources, like the Furre! RPG) is eating of any sentient being, and is generally frowned upon. So perhaps one day it would be against social mores to eat Everything, if some theories come to be true.

It would be difficult to survive in Roguelike games if sennibalism, rather than cannibalism, carried a penalty--but given that some people can ascend with a truly vegan Monk character in Nethack, it might not be so bad.