To give a proper answer to this I would need to explain inherent differences between Western and East-Asian cultures which would take forever, so I'll summarize. In East-Asian countries there is something called "Cult of Cuteness". It mainly has to do with the way Confucianism structured society and family life, where the elderly were at the top of the pyramid and children were at the bottom of it. The "Cult of Cutenes" is a belief that creatures that are pitiful, powerless, and incapable of doing things themselves deserve to be taken care of and protected. This pitifulness is in turn their power, because it compells others to come to their aid. The most accurate translation of the Japanese word "Kawaii" is "Pitiful", rather than cute. This is in itself the root of "Lolita" fashion, to present yourself as pitiful and defenseless as possible so that others come to your aid. It isn't inherently the idea of wanting to be a child, but of adopting child-like characteristics to use the willingness of others to help you.
How is this relevant to the question? Well, it is my understanding that Lolicons are appealed to this in itself: The fantasy of helplessness, and most (most, not all), are capable of understanding that this is a fantasy that can't be experienced in real life but only in the realm of anime. This is, again, my understanding with the more reasonable bunch, so I can't claim this applies to all.
As for if it's fair game to beat your meat to them, I tend to now want to think about what other people are into. I'll elaborate. Many of these character aren't real, therefore information about them is more often than not arbitrary. Take Uma Musume and Blue Archive. Both are games set in a high school environment, but whereas Blue Archive discloses characters' supposed ages, Uma Musume does not, thus maintaining plausible deniability. Has this prevented people from sexualizing high school horse-girls? Has this at the same time raised enough of a stink to want to ban everyone who participates in the thread? There are many characters that do not reasonably fit their assigned ages and you wouldn't even know they're supposedly 17 without looking up the wiki, just as Unredacted TND found out with Lam above. Take pic below for example. This isn't a trick question, would you be able to tell the characters' ages from just their sprites, without needing to look it up for confirmation? Two of them are 18.
Does this make jerking off to lolicon moral? Probably not, but it's a fact that lolicon exists. Just as furry, vore, guro, scat, or any other disturbing fetish out there, in a drawn format or otherwise. I personally don't plan on ever posting or linking to lolicon on this site. Well, as long as i'm still around. My argument has always been that if you start criminalizing thoughts according to what is considered socially sensible today, you're opening Pandora's box for anything that you might like which will be considered unacceptable tomorrow. This site itself has been taken down multiple times because it isn't currently considered socially acceptable. Human sensibilities that aren't anchored to the Divine are always fluctuating, always changing, and never consistent.
