Surprise! Surprise! Just the thought of being cheap and not working for it like a respectable role-player would is not quite enough to stop people from abusing a loophole resulted from an error on Kishi's behalf.
Now I've heard quite a bit of complaints about this matter from both average and elite role-players. Some lacking the sharingan resets, some going about EMS the right way, some having not managed to get an EMS the right way but refuse to go the cheap way. So are the latter just idiots when so many just trade eyes and get it?
Alas, here is my detailed list of arguments:
the fact that anyone with the mangekyou could obtain EMS in such a way would be more than enough to void such crap, hell, I have more respect for those that just go and claim it, they don't go abusing pretend loop holes.
For starters, merely because Kishi messed up via ambiguity or bad wording, does not mean it's something to go ahead and abuse. There are even cannon stuff that got voided for being a god mode.
Most importantly, there is proof that robbing the eyes of an Uchiha sibling is the way to go about it. There is zero proof to merely trading eyes being possible. Just cause it isn't in the manga doesn't mean it's not possible is not a valid argument. There is proof to it clearly not being something meant to be obtainable via trade.
The weird statue representing the EMS has 4 sharingans this further suggesting that one is indeed left w/o such. And that it requires all 4 eyes in some way.
http://i1082.photobucket.com/albums/j361/Rares_Dragota/chapter-3861.jpgIn the same link he mentions the many sacrifices taking place in the history of the Uchiha clans in the attempts to obtain EMS, that more than strongly suggests that merely trading eyes, was NOT an option.
Lastly, we have the most known means of obtaining the mangekyou to begin with, the EMS is bound to be similar, given that the mangekyou is known for it's sacrificial requirements.
To sum it up.
Pro voiding the cheap method: Goes against Uchiha clan history and means, the only known series examples did not include merely trading eyes. The statue thingy, that further provides us with the fact that two can bear the EMS from the same 4 eyes, by appearing after being presented when the EMS was mentioned, behind Itachi and with just two sharingans and two empty sockets.
http://i1082.photobucket.com/albums/j361/Rares_Dragota/chapter-386.jpgAgainst, pretty much the famous "Just cause it isn't in the series does not mean it's not possible" something often used by those that are commonly accused of passing the creativity/god mode line.
However even that falls apart, if not for contradicting Uchiha history, and not for the 4 eyed and 2 eyes 2 empty sockets statues, Itachi states it himself. "To obtain the mangekyou one must kill their best friend, and for EMS, one must kill their kinsman" in the second link I've provided.
I think I'll start to attempt and empower the voiding of this obviously wrong trend, everyone is welcome to follow suit.
Well this is all I have, I'll probably lack future input.
Though just like in the mangekyou case killing may not be a must given that Madara didn't kill Izuna, it is stated that for an Uchiha to give up his eyes is like suicide, further goes to show the sacrifice that takes place regardless. The eyes find new light in the new body so hell, if exchanging was a viable way. Izuna could have juts incorporated the blind eyes of Madara. The point of this was not the need to kill to begin with, merely the fact that two mangekyou pairs will NOT result in two EMS ones. Oh well, I believe my point was made.
It's well known that the only manga examples we have are MS users that got well advanced in the doujutsu before obtaining the EMS, hell, we don't even know if going blind is not a prerequisite. As such,
gradnmaster Uchiha, would be a prerequisite to obtaining it by stealing the eyes of your kinsman.
Note: the 4 resets requirements goes to stop two resets from claiming what would only be acceptable for 3, 4.
Note2: For the sake of saving time, I am updating this as the conversation advances.