Would it be morally fair of Nexon to ban buyers/sellers of NX? I think not.

The ToS must be considered when we talk about ethics in this case though. There is no such thing as unconditional ethics that can be applied universally.

Of course there is. All of Lincoln-Douglas debate theory is built specifically on this concept. There's tons of philosophical papers on this very discussion, certainly enough to warrant the possibility of universal morality.

I think we can loosely agree that Nexon America subscribes to this theorybusiness ethics as do most American corporations. From their point of few, The selling of NX for virtual currency represents a loss or at least potential loss of profit.

There are two possible out comes of a such a transaction in the games current state.
1. A successful trade of mesos to NX for a market determined exchange rate
2. Someone scams

The 2nd scenario may be briefly addressed. The person scammed, frequently the NX purchaser, becomes upset. They get angry and post on Nexon's forum or log a ticket. Nexon, unable/unwilling to do anything about it, then becomes the target of the customer's frustration making them much less likely to purchase NX in the future. The loose profits.

The first scenario is much more complicated. To understand how it affects Nexon's profits and their obligation to share holders we must determine two things.
1. Would the NX seller have bought NX for alternative purposes when unable to sell directly for mesos?
2. Would the NX purchaser have bought NX if unable to purchase for mesos?

From personal experience, I am inclined to believe that most NX sellers would continue buying NX even if unable to sell and use the less reliable means of conversion such as Cash Shop Surprise boxes, Gachapon, Meso sack, or even cubes. Perhaps the more relevant question is, would the quantity of NX purchased remain constant? This is a much more difficult question to answer. Nexon's officially sponsored methods rely on gambling and offer a lower average rate of return (or else NX price rises to compensate). Does a lower rate of return incentivize consumer spending? The answer is usually no. That's why corporations invented sales. It would take some significant research to determine the exact reaction, but I would personally guess Nexon loses some profit since people are more inclined to spend for a flat rate of return than gamble.

While there are definitely a subset of the population that absolutely refuses to buy NX, myself included, for various reasons, experience tells me the majority of people do purchase NX when frustrated by the lack of availability in NX sellers or when the rate rises beyond reasonable. By prohibiting in game purchase of NX, Nexon increases the number of purchasers.

So which wins out? Do the frustrated people buying NX balance out the frequent sellers who now purchase less? I have no idea! I'm not sure Nexon does either.

From their perspective, it's a moral gray area of undetermined profit margins. I suspect this is why we see key differences between Nexon Korea's corporate strategy and Nexon America's. We have long had a bastardized version of KMS' Cash Trading system. All the necessary components are there and we're long over due for it based on the usual localization schedule. We can obviously conclude that GMS has deliberately chosen to forgo the only safe way to convert NX purchases to mesos.

I'd like to hope this is because Nexon America has done effective research on the idea and concluded it would be unprofitable. This may be a bit optimistic given Nexon's business practice history, but we're no privy to their internal research.

From a consumer point of view, trading NX for mesos via "trust" or Cash Trade can only be a good thing. It's another option and allows the game to truly be free to play.

To conclude:
Is is wrong to trade NX for mesos?
From Nexon's point of view, probably.
From player point of view, of course not.

This was a really long explanation of the obvious...

I buy NX for mesos and I will continue to do so regardless of the current bannings. Why? Because I refuse to pay for this shitty service, because I have no money, and because I find it the game more challenging/fun without buying my way to high damage. Am I hurting Nexons profits? No. I wouldn't buy NX for $ even if they were banning every time I bought NX for mesos. Is this true for the majority of people buying Nx for mesos? Probably not.