I think the origin of Naraku was poorly developed. Onigumo's involvement was minimal, his connection with the readers is non-existent, no one cares, no one even hates him because, so far, he has been insignificant to the story. If there were more flashbacks with him, showing his thoughts, people could make a fairer judgment of the character. And then, when it revealed that Naraku wasn't him but a mixture of various Youkai, it would catch people more by surprise. You could just take the flashback from this chapter and turn it into a bigger story!