What IS this "RMT" you speak of?
Raph Koster, well-known game designer and blogger, has posted an exhaustive analysis of the practice of purchasing in-game items and gold for real money at his blog. It's one of the best write-ups about this issue that you're likely to see, so check it out if you have any interest in this type of thing.
1) Is this a new idea?
No, of course not. After all, bind on pickup, level limits for grouping, level limits for item usage, and so on are exactly this design, just now it gets applied to currency (thereby making it, well, not actually a currency). This is the natural extrapolation of that, in some sense, except that if anything it does not go far enough many systems simply acknowledge that there is no currency and turn it into points instead, which is more accurate.