First of all, he was arguing that characters don't have to be carbon copies of the target audience, not thatthe target audience is "great japanese people", and second as it is right now the characters are nothing like the target audience.
Most manga actually feature people whose talent is at the top of their world, even "realistic" manga. Light is supremely intelligent, Hinomaru Zumou and pretty much all battle/sports manga feature main characters at the prime of their world's physical ability. Mashiro is unrealistically skilled in art for his age, Takagi is the actual /best/ student in /all of Japan/ (without studying to add extra unrealisticness), Raku Ichijou is fucking amazing at accidentally getting girls to want his dick, the same goes for all other romance protagonists.
Basically, my point is that the characters are always uniquely great and nothing like the target audience. As it is right now, JUMP's characters are all already "great Japanese people." Purposely pathetic or average characters like Tsuna are the exception, not the rule. There is zero correlation between traits of the audience and traits of the characters, aside from the very basic age and gender. The similarities end there.
