Interesting bitsharestalk thread on the subject here:

https://bitsharestalk.org/index.php/topic,23691.15.html

Basically bts seems cool and useful on the outside but when you look deeper at it, you realize its just a complicated, low liquidity, faux-decentralized, scammers dream platform. Having a well designed and robust referral system wont garner new users, when bts doesn't excel at filling any niche role. It does a bunch of things in complicated clunky ways.

Attracting liquidity is the hardest part, and that's after they've gotten many of the other aspects mostly right.

Just look at the effort ERIS Exchange has gone through promoting their futures contracts over the past few years:

https://www.erisfutures.com/EE/Eris_Swap_Futures_Overview.pdf

Also notice how many platform partners they have, and how far they go to make people feel "safe" using it. And look at the fees:

50 cents per side, per $100K NOTIONAL! That same size trade on poloniex (with all its issues and risks) at .15% ADD LIQUIDITY (not remove liquidity, which is even higher) would cost $150!

https://www.erisfutures.com/fees

Any wonder why the really big traders are still mostly sticking to the much less expensive regulated trading exchanges?