The way I define whether something should be illegal or not is by simply asking two questions: was it consented to, and does it hurt anyone?
By this question, if we analyze the pedophilia issue, we can see that real life child porn as well as sex with children should definitely be illegal because children cannot consent and they are definitely being hurt.
But by the same definitions, we can also see there is no reason to ban loli/drawn child pornography, because a drawing doesn't need to consent and you can't hurt a drawing. Because it's a drawing
Sure, loli porn disgusts me personally, but my emotions and opinions on it are irrelevant. Simple logic states that there is no reason for people to be robbed of a freedom unless that freedom directly hurts someone else.
If anything, banning drawn child porn can actually end up hurting innocents. When it comes to hentai, yuri and yaoi, for example, loli porn is often found on the same sites as adult porn and sometimes even hidden within what at first glance seems like adult porn. And not only that, some douchebags that don't understand manga like to point to the eyesize of people present in adult hentai and claim that a character is underage because of it (despite having lets say a DD cup, a job and an apartment of her own). This means that we are running the risk of punishing people who aren't even pedophiles to begin with, and ruin their lives just because they accidentally ran into porn that they hate just as much as the average person does. Laws exist to protect the innocent, not hurt them.