What about the margin trading? What's wrong with it?
Currently, you can be margin called even if you have enough balance to cover your entire debt in your account, because MPA contract is not smart enough to be aware that no debt exists until bitAsset is transferred from the issuing account. To close your position, you need to add funds
on top of your 2x collateral first, which is nonsense. and if you have, say, 1000 USD worth of BTS in your account, and you want to short bitUSD, you need to issue 500 bitUSD, sell them, add BTS to collateral manually, issue 250 bitUSD more, sell, ..., keep repeating this infinite number of times until you get old and die. This is not how shorting should work. You should be able to go ahead and put 1000 bitUSD sell order on bitUSD/BTS market. Alternatively, you could put 500 bitUSD order on any other market or send them to your friend. Or, you could put 800 bitUSD sell order on bitUSD/BTS market
and send another 100 bitUSD to your friend at the same time. In all these cases your position would be covered by 2x collateral all the time, because bitUSD which is sitting in a limit order is not your debt, and when the order is (partially) taken, a smart contract which is really smart would top up the collateral as needed. This is how shorting works on other exchanges.
I repeat myself, decentralized margin trading is an awesome idea, and a greatest selling point of bitshares. It should be advertised proactively, because people trade on margin like crazy on other exchanges, which indicates that a huge demand exists. But, it would be easier to convince everybody to switch to DEX if the major flaws were fixed.