Because you have Mastercoins and because Mastercoins are stable. I am not convinced Colored Coins will be more stable than Bitcoin but if it can then it will do well. For me I like the fact that Mastercoin provides an escrow because I shouldn't have to trust the issuer to honor the contract and having Mastercoins as escrow will allow for people to have a place to put their wealth to use creating new currencies in a way which isn't too much risk. I also like that Mastercoin can act as a unit of measure for the entire system where all wealth in the system can be determined by an unchanging Mastercoin. There will be very minimal inflation in Mastercoin compared to Bitcoin and that means a lot less volatility and a much better measuring unit.
If you like Colored Coin then use it, but if you like Mastercoin then use it. Some people will certainly pick one or the other, some will use both. Some will use Bitshares and some will use all three.
Why wouldn't you use all three?
You could use all three but what I am interested in is what system is best for asset management such as stocks for a company. The thing with Colored Coins from what I understand is that it IS Bitcoin. It is just about assigning certain outputs with a certain value other than their corresponding Bitcoin value.
Exactly, it is Bitcoin. So if something happens to Bitcoin what happens to your stock?
If something happens to Bitcoin then Mastercoin can just use another blockchain. If something happens to Bitcoin then Bitshares has it's own blockchain. Colored Coin has no alternative so if something happens to Bitcoin such as if it gets politically attacked, or if there is some problem with it found it will affect Colored Coin because ColoredCoin is not platform independent.
Unless you are a business oriented individual are prone to believe that Bitcoin will be the only cryptocurrency, that Bitcoin will be the final cryptocurrency, and that whatever your doing should die with Bitcoin, then perhaps it's in your self interest to diversify.
For that reason if I had to choose between Colored Coin and Mastercoin I would choose Mastercoin. Between Colored Coin and Bitshares I would choose Bitshares.
Additionally I would choose Mastercoin because I think you need a unit of measurement. For example the amount of energy in the universe is the same from the big bang right now and it never changes. Energy is never created or destroyed. This gives us the only sense of stability we have in this universe and allows for all the laws of physics, structure, and clarity in the electromagnetic spectrum.
Bitcoin in my opinion is not a good foundation from which to build a unit of measurement because it's still in an inflationary period. Mastercoin is in an inflationary period too but we know exactly the rate that Mastercoins will be created and the bonus Mastercoins wont create any volatility because they'll be used for development and we are talking an nominal amount.
So for our purposes Mastercoin will be fixed in time/space, will become very stable, and will serve as a good unit of measurement. I don't believe Bitshares will be able to do this as well because it too will be mined, but I think at least with Bitshares that mining will provide redundancy and diversification. I think redundancy and diversification are good for the long term security of cryptocurrencies in general because if someone could destroy the Bitcoin blockchain they would not destroy Bitshares or Mastercoin but that would destroy ColoredCoin's Bitcoin implementation.
There is a way around this which involves implementing ColoredCoin on Litecoin, Primecoin, PPCoin and Freicoin. I think if it's implemented on enough altcoins then you could theoretically have redundancy but then you would have the problem of volatility and all these separate implementations would run any chances of trying to use it as a standard unit of measurement.
How many atoms exist? Well if the number changes depending on how you look at it then it's impossible to form any includes on anything in the universe. That number has to be fixed, set in stone, unchanging, and then we can say gold has an atomic weight of 196.966569. We know gold has 79 neutrons. We know where gold rests within the 10^78 atoms in the visible universe and that says something.
ColoredCoin wont be able to do that because it's not ever going to be a precise measure of the value of something else because it's abstract (Bitcoins posing as ColoredCoins) rather than something concrete (set in stone). If I ask how many ColoredCoins will exist on the Bitcoin blockchain no one can tell me that answer. If we assume every Bitcoin can also be a Colored Coin that is the closest thing to an answer I could come up with.
If I ask how many Mastercoins will exist in the Bitcoin universe the exact measurement is 619478.59338440. This number will not change and cannot change ever.
Knowing this and knowing that most of the Mastercoins that shall exist came into existence instantaneously, it can become very stable. If you want to know how many atoms are in an oz of gold you can ask, and if you want to know how many Mastercoins are in goldcoins you can find that out as well. The amount of Mastercoins which make up a gold coin is critical for measuring the value backing the gold coin escrow. The gold in their vault might or might not exist but we will know the value in their escrow exists.
The main use case is company stock. You have to believe in the company of course, but you don't need to rely on any centralized, cumbersome stock exchange.
And this is why, Meni, that Color Coins are generally irrelevant. Bitcoin was interesting because it had ZERO TRUST, not only at the technology level, but the financial level as well. Nothing was BACKING it. Color Coins suggest BACKING and exchangeability, thus you've removed zero trust AND you can safely remove the technological zero-trust(POW) from the equation as well. This is what has been done with Confidence Chains.
This is why Mastercoin relies on escrow. You don't have to trust the issuer but the system definitely works better if you can. The other scheme is contract for difference which doesn't require any trust at all except in mathematics.