To be honest I can see several reasons as to why CMC won't list 421 coin at the moment. 1 421 is only listed on one exchange CryptoHub which doesn't rank all that high when it comes to volume for exchanges. 2 421 doesn't have much volume at the moment, yes we get some good days where the volume is good but it needs to be more consistent before CMC will take a look. I believe that in the future we will eventually see 421 listed on CMC but for now we just have to wait. Maybe another exchange would help out? The problem now is that almost all exchanges charge an outrageous listing fee.