I can sympathise with exchanges wanting to be careful about which coins they add. I run a server with over 50 coins, just for my own private mining and hodling, and even my modest usage requires a fair bit of TLC. A client that runs fine on your local Windows machine may not work so well at an exchange once hundreds or thousands of transactions have passed through its wallet. A couple of misbehaving clients (high CPU and/or HD usage) can impact upon the others and begin a downward spiral of resource starvation which affects the entire server. There is a cost involved because you cannot simply run 200 coin clients on a single server.
Coin Servers are not that expensive, and PoW coins hardly pull anything if you only run a wallet.
PoS coins with a modern CPU , should easily handle 5 different coins per machine, more if you are not staking.
FYI: Cryptsy is Staking PoS coins.Cryptsy trading volume for 1 day , $152,540 .
Don't tell me that cryptsy or bittrex or any other major exchanges don't have the resources to have more than a few PCs.
Truth of the matter, is the only thing that makes sense is they use it to try and increase liquidity in the other coins we are paired against. We have a LTC & XRP markets on cryptsy , but no BTC or USD,
Reddcoin has a BTC, LTC, XRP, & USD markets, their marketcap & price is currently lower than ours, and some would say well they have more trading volume. Did anyone ever think, they have more trading volume because they have More Markets on the same exchange.
So when we buy zeit on cryptsy, we are pumping the ltc , because we have to buy it first.
And when we buy it they collect the trading fee of 0.250% twice, once on the BTC to LTC and a 2nd time on the ltc to Zeit.
They make more money by not giving us a BTC market. Plus if they had a direct USD pairing , most of us would not even buy btc, just buy zeit direct and save a trading fee.
FYI:
Some exchange don't use the resource excuse.
Cryptopia gave Hyperstake it's very own server , since it was not playing well with CPU usage for them.
1 coin received its very own server, and they don't have cryptsy volume yet, keyword yet.