Actually I don't see now a decentralized exchange that could give traders a lot of options to trade as they only list coins with low volume and in general decentralized exchange has a very low volume even if you combine all of them and compare it to centralized trading sites.
This looks like a "chicked or egg, which one's first?" argument. Traders argue and complain that dex has low volume but how will it gain volume if they don't use it?