There's tons of lousy coins on exchanges now that have small marketcaps and less than 500k volume.. this is so unusual.
Indeed. But the NEM team really hit it out of the park to get onto the best alt exchanges at the beginning.
Japan aside, what would really drive things to another level would be GDAX, Bitfinex and Gemini. Those places would want some extended track record before considering it. There are other coins that have had some insane volumes too but only ETH caught enough of their attention recently and it had to become a juggernaut to do it.