Your answer to one kind of proves my point. If your parents help you order a game, then it is their responsibility (not Nintendo's). Heck, it is always a parent's responsibility (why did I need so many words in order to come up with this :lol
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As for two, I'd love to point out that many people who love Nintendo nowadays, do so because they grew up with Nintendo games. For a company not only short-term profits, but also long term customer binding is important. Which is why games like Pikmin 3 are delayed. I can find myself agreeing to the risk of losing the family friendly image, though.
It's good to have a discussion. The more relevant arguments we have, the more likely Nintendo is to listen, as they will ask themselves those questions too.
Speaking about likelihood of listening,
Actually, I'd advise against it. As this campaign is on a roll now, it is better to keep it at one. I would love a general Nintendo account system (Wii U and 3DS), but now is not the time. If we would start many petitions at the same time, we risk that Nintendo ignores them all.