I'm glad my op started this healthy discussion, even if I'm not an active participant myself.
I just wanted to state my opinion here for the record.
I just
started another thread that hopefully will be less technical and more high-level, copy pasting my post here:
There have been several well known bitcoiners that tried to convince J.R.Willet to move Mastercoin to an altchain, instead of using the bitcoin blockchain. Willet's opinion is that Mastercoin should stay on the blockchain, and I fully concur. Here is my reasoning:
It is easier to implement Mastercoin on the blockchain. The entire concept of mining "vanishes", or actually is satisfied by Bitcoin miners. This means the security of Mastercoin is on par with Bitcoin (up to potential bugs) ... there is no way to 51% attack it.
The same could be implemented using merged mining, but no matter how you look at it, merged mining is technically a more complicated solution, because it requires an entirely new blockchain one needs to reason about. You need to think about the hashrate of this separate blockchain and to encourage miners to merge-mine it, things that are just not needed when you directly encode things into the Bitcoin blockchain. As far as software development goes, I'm super lazy - I do not like to do something complicated if I can do something simple that serves the same purpose.
Now, it is true that this "burdens" the blockchain ... in the same way that Satoshi Dice does.
However, this burdening is something that Bitcoin users and developers will just have to live with. Nobody is the boss of Bitcoin, and any standard Bitcoin transaction (like Mastercoin transactions are) are legitimate transactions that Bitcoin simply has to learn to deal with. There is just no feasible way that I see that Bitcoin developers could ban such transactions (please enlighten me if I'm wrong).
Bitcoin is the future of finance, resistant to hacking, government censorship and regulation. Do you really want to base that future on asking other people to pretty please "not abuse it for you own purposes"? This is not the answer. Bitcoin has to be made scalable enough to meet its role as the one major, global, world currency.
Mastercoin developers have no intention of disrupting Bitcoin, and will gladly adapt to any
friendly encoding that the brilliant minds of these forums will propose, as long as it doesn't harm Mastercoin (using non-standard transactions that are relayed more slowly is not an option at the moment). The Bitcoin blockchain must and will remain neutral, and if Willet hadn't come up with Mastercoin encoding, someone else would have created something similar sooner or later.
