Lisk is pretty new, i dont find any good reason for adding it to coinbase, and coinbase works more as a wallet for bitcoins, not an exchange.  So why dont you hold your lisks or its own wallet? it is not difficult.. anyway, i know that lisk has a great future, but the market is unpredictable, and maybe lisk can drop a lot, because it does not have that much volume that it has a few weeks ago.