Cabin crew are aboard the plane to work; they are there for safety reasons and to cater to passengers' (reasonable) needs.
As a retired captain I don't think that I need to be reminded of this. So at the end of a long night flight would you be happier if the cabin crew were alert or knackered after just dozing in their seats. I was trying to get an intelligent answer from maybe an EK employee who knows the reason behind this restriction. So I repeat, why can't EK cabin crew use the bunks to grab a few hours sleep at night when their duties are light - not all at the same time obviously, before some bright spark picks on that one.