Counter-argument: "We don't even need cryptography!"
Money has never needed 'cryptography' or any kind of meta-layer obfuscating technology to implement a fundamental monetary property (such as fungibility). Any monetary medium that works will have self-generating fungibility - like the cash drawer or gold's low melting point.
If I melt down 10 gold coins to make a gold bar and then use that in a transaction, I'm not "hiding" the fact that I'm making the transaction. The fungibility does not come from any form of encryption, but rather from the fact that gold coins could be combined from 10 distinct "inputs" into one indistinct "output".
It's an inherent part of cryptocurrencies that that is possible - which is why they make an almost perfect monetary medium. Darkcoin / Dash levers that characteristic. I'm not saying that a cryptographic approach like cryptonote isn't interesting or potentially useful in many cases, but I'm saying it's not necessarily the optimal solution to botcoin's fungibility problem from a monetary point of view.
In this case, money is being transacted across a communication medium thousands of years in the making. In doing so, it's transmitted through an input terminal (computer, phone, CC, etc..) by means of digitally constructed software on hardware that's designed to interpret our thoughts and perform actions with the click of a button. Anyways, after clicking that button, it's transmitted through an internet relayed through a moderately unique IP address that's recorded through your ISP, and then generally some more software and hardware interaction along the medium, until it gets to it's point of use where it's again generally met with a terminal (be it a POS terminal, another phone, etc..). Sure, you can make the analogy that it's like taking cash out of your wallet, but in this case it has to go though all of that, and it's enforced by a cryptographically-secured universally available blockchain file.
So saying "it's just like digging gold out of the ground and handing it to the guy at the corner store and putting it into a bank" doesn't make it so.
These things we're dealing with, they're not 'money'. They're what we define to be money. They're cryptocurrencies, that are indeed cryptographically secured, from the cryptographically secured PoW to prevent double spending and network havoc, to the elliptic curve designed to both send someone money and receive change back. Cryptography is the very essence of what we're dealing with here, it's the root of every single thing on this board, even DRK I promise you.
Money does need cryptography, how do you think you do online banking without everyone stealing it?
When it's not "obscured or 'hidden' " then it loses that very powerful descriptor of being fungible. Take for fact that certain bitcoins have no value on coinbase, or btce - it's because there is no 'obscured or hidden'. Not in the sense that wrong doing must be covered up - but in the sense that we all must maintain a totally fungible transaction medium, despite that. We can bear the cost of the inefficiency ourselves, because the necessity to transact is paramount to catching criminals just as we have been doing for years. It's just worth more than that.
I get what you were saying about mixing them, but there's a whole lot of inbetween that you just can't argue by analogy, and the point made above about the TLA's really does lend to the idea that whatever 'mixing' is happening with masternodes is done so in a manner that will be traceable if the private key is compromised. So the argument that a view key can be compromised in the same being an actual edge over XMR just doesn't hold water when the two are compared.