Great answer - got it!
I don't think that is a good answer at all.
So, we can make new currencies with new wonderful functions based upon this 'mastercoin' protocol. But there are only 500000 MSC. So, what currency is going to be based upon something only having a unit of 500,000? Of course, one MSC is very highly divisible - so you only need one MSC to make a million CoolCoins - each worth about $100 lets say. Then another guy takes 1 MSC and makes two million SuperCoolCoins with even better functions - these are worth $500 each. Well, there isn't much demand at all for the other 499,997 MSC because CoolCoins and SuperCoolCoins and maybe two or three others are all we really need. Nobody wants the other MSC. OK - now we have 'smart properties' and 1000 companies each buy 1 mastercoin, divide it into 1 million shares, and use that for their stock issue. I am still holding my 100 MSC and nobody wants them because there are 499,000 still doing nothing. They are easy to buy until they become scarce. But because we'll never have 500,000 projects each of which consume one MSC and divide it down to one million (or more) pieces, they will never be worth much.
Specifically, MSC holders do not own this sexy protocol being developed. The protocol will be free to copy by anyone and they can run their copy right on the same BTC blockchain. Even if demand for MSC does finally get high enough to make them worth $5 - Anyone can 'relaunch' an identical protocol and create a Billion MSC2 leaving MSC holders with nothing.
It is important to note - MSC holders bought those coins with good money and that money is being used to devo the protocol. When it is all wonderful and developed, JR has done nothing to maintain ownership of that protocol. A competitor will just come in, scoop it up, restart it on a parallel effort and MSC holders will have nothing.
JR says the big guys won't be able to do that because they will be too 'far behind'. Ask Microsoft how they felt when everyone laughed at Internet Explorer in view of Netscape. Netscape was sure that Microsoft was just way too far behind. Netscape was out of business about ten minutes later.