One thing I find troublesome in this game is to an extent you are forced to level certain classes if you want to remain at a competitive level. Perhaps you had no thought of leveling Archer but if you want that Chameleon ability so you can do greater burst damage then you better be prepared to invest yourself in 42 levels of Archer just so you can improve your damage on another class.

The idea is basically why not allow people to exchange Guild Marks for abilities from other classes so that they can use those abilities without being forced to level x class. By forcing them to level x class it leaves the door open that they may be forced to play a class they don't want to play because of the metagame and rather then the person enjoying what they'd like to play they are instead forced to play roles outside their comfort zone just to join in group activities.