Rather than present a "technical" justification I will simply present an analogy.  You have 3 players in the market, someone who wants to buy A, someone who wants to sell B, and someone who knows both A and B, C.   

If A and B do not know each other and C knows there is an opportunity to buy from B low, flip, and sell to A for a profit then he will make the market and keep the profit.   If A and B know that C will be doing this then they have incentive to minimize the spread.

Perverse incentives that could result... users must create many small bids/asks to get the best possible price.

Also the process of giving people exactly what they ask for makes validating transactions much easier because I can search for equality rather than >= and thus avoid ambiguous cases.

I think I've figured out my misgivings:

In your example, B has an incentive to raise his ask price; A has an incentive to lower his bid price. That's all well and good, but here's the the problem: B's ask price no longer accurately reflects his true willingness to sell, and A's bid price no longer accurately reflects his true willingness to buy. Since they don't know each others' willingness to exchange, B could raise his ask price above A's bid price and make the market illiquid.

So there's the dangerous perverse incentive: giving people exactly the exchange rate on their order incentivizes them to act like they're less willing to exchange than they really are, and market liquidity suffers.

This is why eBay doesn't charge winning bidders their bid; it charges them the bid of the second-highest bidder, because then bidders do not have an incentive to under-represent their willingness to buy. eBay's goals are essentially the same as BitShares'; i.e., they both want to facilitate the highest possible number of exchanges.

I can't speak to your last point; it could be that the technical aspect of validating transactions wins in the end.

Why hasn't this gotten more attention?

Maybe it's just my insane curiosity, but I'd love to know what you have in mind...

Here's my take:

A BitUSD is essentially a certificate that says “The BitShares network promises to pay the bearer $1 worth of BitShares upon request.” So suppose at some point a BitUSD is worth 9 BitShares, but $1 is worth 10 BitShares. In other words, BitUSD is trading at a bargain - if I buy 90 BitUSD, I can redeem them for $100 as long as I trust the BitShares network to make good on its promise. So I will go and buy as many of these cheap BitUSD as I can until the price of BitUSD again matches that of fiat-USD.

Seems very clever - what if you specified an asymmetrical fee? Charge more to convert MMC to BTC than BTC to MMC; remove as many barriers to MMC acquisition as possible.

I'm a newcomer to the MMC community, and I'm excited by the possibilities of this coin. One of the things that has frustrated me, however, is that the voting process seems unnecessarily opaque. Is there a simple way to see election rankings other than manually searching through every vote in the results and adding up address coin totals?