Many people have made valid points on this issue. Like I said earlier, dawsey28 is right. The people who create Manga are not the ones to blame, it is the people who sell Manga who are at fault for children under 13 buying Manga for older age groups.
The debate about ratings is not about if someone has a problem with reading more mature Manga, or sex, or violence, etc. The ratings are a categorization of suitable ages for reading Manga.
Let's not forget that, yes, it can be annoying to hear someone drone on about nudity/violence...blah...blah. If someone who is of an appropriate age has a problem with it, it IS their problem and they are entitled to an opinion.
I don't have a problem with nudity, but I have my limits. I refuse to read some things entirely or I just skip that scene. That works for me.
If a parent lets their child read 16+ Manga, then I say let them read it. Some kids can be very mature for their age.---Don't misunderstand me. I don't mean that an eight year should read Adult Manga. I am thinking about someone who is at least 13.