To me, the question of people spending real life money on in-game things has been this: why are people paying not to play your game? What is your wrong with your game such that people would rather spend time at work than put in the hours in-game to accomplish whatever they are buying?
Pause for a moment and consider what an indict of a game RMT is: someone will pay hundreds of real life dollars to skip large chunks of your content. If this were just an eccentric few with odd tastes, that would be one thing, but there are thousands and thousands of accounts involved.
If the end-game is the whole point, why are you making people wade through the PvE leveling content? Be Guild Wars: make the content available for anyone who wants it, but let anyone skip it. Don’t include a level grind out of habit. If you included a level grind to give people a sense of investment and commitment, do not be surprised when you see large perverse effects from this system. You have added a farming tool that is contrary to your needs but as fully open to exploits as anything else.
Theoretically, we use levels to spread people across the content and pace its consumption; if people are skipping large chunks of it, something might be wrong with that content. Do not engage in self-reinforcing delusion that there is no problem: “Why should we make more lower-level content when people are just going to powerlevel through it as quickly as possible?” If the best part of your game is the low-level content, people will make many alts to enjoy it from many perspectives. If you devote all your time to one part of the game, yes, people will burn through the rest to get where the “real game” is. An empty zone is a waste of programmer time that could have been spent making the world a better place.
Levels are not the only things we grind. How about gold? There are good ways to have money sinks, and then there are blunt instruments that might as well have been checks written directly to the farmers. Why not charge hundreds or thousands of gold for a mount? I am sure that players will enjoy however many hours of camping that takes. It will get them in good habits for the endgame grind of the same raid monsters every night for a month.
Many players will naturally find the most efficient thing and do it repeatedly on their own. You do not need to further encourage this behavior by rewarding or requiring camping, nor should you base the rest of your game around these people so that everyone must emulate them to see any progress.
If your game feels like work, people will pay not to play it. Or maybe they will just stop paying to play it.