Recently I have been hearing a lot of complaints about high profile exchanges that only add the latest scam pump and dump coins and not honest coins with a bright future, while this may be the case at the end of the day most exchanges only care about making btc through high trade volumes.
A lot of people were surprised when mintpal added whitecoin, infact there was plenty jokes going around about whitecoin being created after blackcoin on btc-e and poloniex troll boxes because we knew it would start the color coin revolution and today we have a lot of colors to choose from.

None of these coins will add any value besides the enjoyment of playing the pump and dump game. Most of these coins won't add real value outside the crypto world and most certainly won't contribute to growing the industry. We all know for a fact 99% of these colour coins will be a distant memory in 1 year from now.

Why Mintpal is smart is because they ride the high trade volumes for new coins added and then will remove them when volumes dip under a certain amount, hell at the end of the day exchanges don't give a shit about crypto currencies that will have a use but low trade volumes, it's just business. Scam coins have matured and need a lot of btc to get listed onto exchanges now, also scam coins need to show some form of "innovation" to make some btc. This is a good thing because it kills off shitcoins and scam coins with no btc behind it.