Waves you mean?
I once had a few coins there, the small volume is not very attractive for traders who have big capital.
So far DEX is safe and reliable. Please try it
Actually bitshares also have their own DEX (Decentralized EXchange).
Why do you think the conception of dex has not gained popularity? why does no one want to trade there?
Probably it's hard to understand and the advertising for exchange is not really much comparing with centralized exchange.