Then poloniex has to ask, will adding waves bring in new users? Probably not. It'll just move volume from other coins to waves. This would mean poloniex makes no money from adding waves and it might cost a few thousand $ to integrate it into their system.
Also waves was released a few months ago. Poloniex usually goes for more mature coins.
If waves can deliver the platform they promised in the ICO then I'm sure poloniex will add it one day.
At the end of the day it is their business and they can choose the coins they want to add. Gulden as I have mentioned before has been delivering on their roadmap and have stated that 1.6.0 is their largest update by far. Poloniex will not add Gulden either and I bet tech wise it will be top 5 after 1.6.0 if not the best.
Poloniex has the volumes from bots and pump and dump groups but volumes doesn't mean they add the best coins.
Guldens 1.6.0 update is likely to expose Poloniex and other exchanges and this is a good thing.
Support bittrex it's a good exchange, if waves delivers on their roadmap it doesn't matter what exchange they on.