The point of buying RMT is to circumvent the treadmill and try to get to the game that's theoretically at the end of it, be that PvP or raiding or whatever. Of course, in most cases it will turn out that the game at the end sucks as much as the treadmill did, but the RMTer still wins out because he found out that much quicker.
Since, in your example, the player finds out he was wrong to believe the RMT shortcut would bring happiness, he was deluded to begin with. That's why I'm throwing around the word "delusion", why those buying RMT are deluding themselves, and those selling RMT are exploiting the deluded.
Most of the "potency-treadmills" you've burned out on, from EQ through WoW, were not of Korean origin :)
There's a very big and easy to find discernable difference between the Korean-Potency treadmills of Lineage 2, RF Online, and Ragnarok Online and the American-Potency treadmills of EverQuest, Dark Age of Camelot, or World of Warcraft. I haven't mentioned this before, but this difference is the Toys to Time ratio. In your average Korean-Potency treadmill progression reaches points, often quite early, where you're expected to grind for 10 or more levels to get one new skill. Often, you'll have your entire set of skills by level 20 and be asked to run another 30 levels with that. In an American-Potency, you get a new skill every 1-8 levels at most, and this rate lasts until the end game when you've a ton of abilities in your lap.
In other words, it's not about how long the developers intended me to play, it's if they bothered to add enough game to be worth that time spent. When you're tired of your toys and have been told to keep playing anyway, that is the difference between a grind and a game.(I underlined all that because it was awesome.

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Important differentiation factor addendum: note that "new skill" (a.k.a. "toys") means "totally different ability than you've had before" as not "upgrade copy of an ability you already have". Simply changing the potency, color, or element is an upgrade (and a minor one at that) not a new ability. Upgrades are better than nothing, but brand new toys/skills are what keep a player interesting for me. For that reason, EverQuest 2 doesn't get as much slack as EverQuest did, because EverQuest 2's skill tree is heavier saturated with copies instead of whole new abilities. Star Wars Galaxies NGE is a total trainwreck for this reason - it's like 30 levels until you get a new ability sometimes - pathetic!
Not enough toys for the amount of grind they ask of me, and I'm doing the same repetitive boring thing with no variation. Enough of that and I'm out. It's that simple. I wonder how many people feel the same way?
The American-Potency treadmills I've had difficulty with are the ones that set the time between level too high for my satisfaction. Guild Wars is a game I can enjoy a lot for this reason - they dump tons of new abilities on players, and provided I'm willing to experiment the game stays interesting. It's a pity Guild Wars doesn't have that massively multiplayer thing going, doesn't feel very worldly at all, but
as a game it's good. City of Heroes has a great lower level toys to grind ratio, but around level 13-16 it slows way down. I'm able to pull some novelty from doing the storylines embedded in the missions, but it's not enough. This is why it's a game I can stomach in short bursts only. Then I start a new character, get a cool new batch of toys to play with, and that lasts until I hit level 13-16 again. A good temporary workaround, but I'll never reach level 50 that way, which is a pity considering Cryptic locked up a whole batch of toys for when I hit 50 (their alien heroes).
I've generously inserted the possibility that Arch-Lord may be different and that "Korean-Potency Treadmill" is a stereotype. However, I've seen enough of their games to assume it's not worth buying Arch-Lord to find out.
Too many developers think that the social aspect is all a MMORPG really offers. I don't think social aspect allow MMORPGs to operate regardless of toys:grind ratio. Rather, the social aspect allows MMORPGs to operate
despite a poor toys:grind ratio for a few unlucky players who friends drag them in. In other words, a MMORPG with both a good toys:grind ratio and a social aspect gots a double hitter, where a MMORPG that doesn't (most) feels half complete. Check out the toys:grind ratio on World of Warcraft, and that's with
weak social dependancy systems.
Anyone know of any games not mentioned yet that have an awesome toy to grind ratio?