Well, Miyamoto was more closely involved in Doki Doki Panic than in SMB2J, so he may have meant Doki Doki Panic/SMB2USA after all. Then again, according to Howard Phillips at CGE, when SMB2J was rejected by NOA (on Phillips' recommendation), it was Nintendo of Japan, not NOA, who decided to convert Doki Doki Panic into SMB2.

Anyway, going back to NSMB2, the Coin Rush mode has this "one more try" quality that makes you want to restart again and again to try to better the overall score, especially when trying to compete via StreetPass with other players (even more so when said players are people you know personally).