There are so many innovative concepts in bitsharesx, a built in market maker would be another one.
However, there are several points I want to make:
1) I like the idea of a built-in market maker as a way to improve liquidity, but I'm worried about the market getting too complex with too many "external" rules. External rules always add a "cost" and an inefficiency. There is a reason why the offset exists, and removing it might not be the best for the market. If the market maker exists within current rules (e.g., buying all shorts listed below spot), that would be ok.
2) I also don't like the market relying on people to feed data into it all the time, I'd like a more natural price discovery.
3a)
We can learn from other similar BTC futures markets: If you played the futures BTC market on
https://icbit.se/WebTrade/Trading.aspx, you'd know that BTC futures are almost always trading above spot. People are bullish on BTC, and believe that BTC should generally be in "contango." (they call it contango, but technically it's not really contango... but that's another story...). That offset is actually very similar to the current BitUSD market, and is due to perceived future strength of BTC relative to USD, the same way the discount of USD on bitsharesx is probably due to the perceived strength of BTSX to USD. When there is a crash, those shorts would be killed. Once that happened the first time, everyone learned their lesson and the market has been significantly closer to spot ever since. We may need a painful correction for everyone to learn to be careful.
3b)
We can learn from other similar BTC futures markets: icbit.se uses variable fees as a way to make the market (adds liquidity to both asks and bids)
https://icbit.se/discount. What if the fee to sell short bitUSD is made much larger than sell/buy? People wouldn't be as willing to sell short far below spot and instead find other ways to buy bitUSD (exchanges), which brings me to...
4) we need more liquidity on
https://bter.com/trade/btc_bitusd and
https://bter.com/trade/bitusd_usd, that is the bottleneck to many arb bots at the moment. (disclosure: i've been working on a market making bot for that. I'm thinking of starting a "market making" delegate where all proceeds get feed into the bots to aid price discovery and peg)