In the articles it was said that the embryos are used as a nutrient source because Chinese people believe that using them as food is good for their health – I don’t know how legitimate this vision actually is, but it might be stated that this situation is also a great example on how people are willing to take a risk by using doubtful means.
Also, when commenting on the morality standpoint, I have to remind that the moral values may differ. In the most of forum member’s societies cannibalism is seen as something undesirable and disgusting, but in the same time there are many cultures which sees it as completely normal process for various reasons (Mars already mentioned an example which would fall under the reason of belief).
Moreover, under very severe circumstances, like famine, a lot of people choose to commit the act of cannibalism, even if it would normally be against their moral principles; at conditions like those eating the dead comrades could be even seen as a normal behaviour (in fact, back again at “hunter-gatherer times” humans might have been semi-scavengers); besides there are know some cannibalistic species (pigs, if an example is needed), so the statement that cannibalism is entirely unnatural wouldn’t be exactly right.
I think that the main explanation why humans are prone to cannibalism only in special occasions is the psychological bonds they form with each other – if a human being would be forced to eat other human being then they most likely are going to choose somebody they don’t know.
(And – no, I do not support cannibalism.)