At this point it doesn't even make sense to join another exchange. This is a buy and hold coin. It is the big boys loss to not have it. Word of mouth is spreading on this coin and soon enough rounds will fly off the exchanges. I can already see an increase in speed from a couple months ago. New rounds don't stick around for long.
Totally agree with you. There is no benefit to anyone for Ambercoin to be added to more exchanges, and in fact as far as I can tell, it would be more of a pain for Ambercoindev to have to send coins to 5 different exchanges everytime coins sell out.