The person who can show me a lawbook that states that e-trades in an mmo is unlegal shall recive a cookie. Yup, Im talking about RMT (Real Money Trade) here.
It might not have been the true intentions of the devs to create games that are highly addicted. Some studies show that mmo-games might be as addictive as conventional drugs. So there's no wonder kids want to get more gold, or better weapons/armors. If there's a shortcut they'll take it, kids these days spend quite a bunch of their money on games. Not just buying them, but they also purchase ingame items for IRL money.
20 years ago these kind of E-trades didn't exist, I do belive it have become so big that it's here to stay. It might even become more acceptable by the players that buying ingame items for IRL-money is no big thing.
So by that said, you do know there'll be gold seller in Tera.