There's a pretty big point people miss when they criticize us adding so many coins to Bittrex.  I don't know of any system to determine if a coin will succeed or fail before we put it on the exchange.  If I did, I'd day trade instead of work on our exchange.

The first 2 parts of the statement are about community demand and innovation.  When we see a lot of requests for a coin in my bct inbox, twitter, and support alias that is usually a signal that people want to trade it.  Who am I to judge what people want to trade?  

We also try to take chances on new business models and algorithms.  We had coins like URO, CLOAK, RZR, NAUT, etc. etc. long before any other exchange did.  We didn't know if they would be successful, but they were interesting enough to get added and let the market decide.  And for every one of those interesting coins that succeed, there are a number of coins that don't.  

The last bit about contributions to humanity is an extremely tricky one.  Almost every "donation" based coin we've been asked to add has turned out to be a scam.  We prefer coins that directly use hash power towards scientific efforts like CURE coin.  And before you suggest GridCoin, yes we are looking at it.  And No, it isn't being added until we get more clarification from the dev team.

Right now, we're looking for 0.1 BTC of daily volume averaged across a 7 day period.  That doesn't cover the cost of each market, but it is enough to show us there is interest in the coin.  We also throw bad blockchains or coins abandoned by devs into the list of coins we remove.