For average Joe, bitshares is missing something like ripple path finding. It makes automatic currency conversions smart way. For example, suppose you save in bitGold and you want to make a payment to online shop which accepts bitUSD, but is no market between bitGold and bitUSD. The system goes and checks different order books, and finds a cheapest path for you like BitGold -> BTS -> BitBTC -> bitUSD. This is a killer feature of ripple and must have in bitshares in order to be accepted by merchants and by general public. It is not trivial to implement though.
This right here, combined with the market maker proposal would be the best way to increase liquidity. With the market maker proposal, the market makers would make money by subsidizing the cheapest pathways. Implement these proposals plus private transactions into the background of a simple UI, and we have a decentralized bank with a tight peg. Once November 5th hits, and people stop with the anti-dilution stuff (hopefully), this is what we should focus on. I came to Bitshares because I saw that I could keep any asset I wanted on the blockchain - I didn't need a bank anymore. I honestly didn't care much about the exchange. I think we should separate the wallets, call one "The Bitshares Bank", the other "The Bitshares Exchange", and market them for different users. We could even have a shapeshift-style trading interface in the "Bitshares Bank" UI which could be great.
On another note, someone mentioned yield for holders, which doesn't make much sense to me because banks are able to do this by investing everyone's savings. In Bitshares, you actually own your money, so in not allowing the system to loan out your smartcoins, you give up that .5% yield for that luxury. If we want yield, we need to make the system more attractive to investment firms. Instead of the yield coming from dilution, it should come from these firms that people can invest in. They would be trading the safer stocks and currencies, making steady money as they do it, taking a cut, giving the investors a return, and profiting bitshares from their actual use of the DEX. This is a much better way to do yield in my opinion.