I was told such a work hasn't been written since the 70's, and that it would be impossible to do one today. The reason is

...it would have to involve the death of grand theory, the inherent inconsistencies in Greek polytheism, the lack of any category of 'religion' among the Greeks, the variety of fringe religious phenomena, the incompatibility between trying to describe religious practice as as outsider vs understanding religious experiences as an insider, the difficulty of ancient sources (especially sources describing inner thoughts), the incompatibility between ancient and modern concepts, how do we reconcile modern anthropological findings on religion (both 'hard' and 'soft' science findings) with the ancient world, and then how we can convey all these differences to readers who hold a Christian normative notion of religion.

What are the problems caused by each of these things, how do they differ from pre-70's interpretation of Greek mythology, and how do they prevent a modern comprehensive work on Greek religion?