The market is pretty good – not perfect but not a problem.
The so called “problem” with the economy is the natural effect of making a game that fun for the average player. It has nothing to do with the way the market works.
Almost everything in GW2 is relatively easy to get in game – this makes the game fun for the majority casual players.
People love getting good drops – people love being about craft with out a big head ache. And the result of this is that modestly hardcore core players can produce or find a great deal of almost anything that is desirable.
The current market is highly efficient with and includes a 15% tank/gold sink. This is a good setup.
Adding more constraints to the market will NOT fix the “problem” that many people have with the economy. All it will do is make a bigger mess.
You cant fix over supply with trading rules – economies dont work that way.