It boggles my mind that Evan didn't design the protocol around micropayment channels, where every full node could be incentivised to mix transactions or vote on InstantX transactions or whatever. It would make the anonymity set so much larger.
Perhaps he thought it's better to make sybil attacks harder. It's basically free to launch as many full nodes as required.
He may have thought that (I'm not sure I buy it) but it doesn't work, because there is still no irrevocable cost incurred for bad behavior. If masternodes are profitable then the bad ones are more profitable as the good ones. In a competitive market this will mean that only the bad ones are profitable.
The argument about "losing the value of your coins" doesn't work because it make a few false assumptions including that cheating leads to total collapse and the inability to hedge with derivatives. Both of these and certainly the second only apply in an immature cryptocurrency toy, not in a scaled up system.