the problem with monk is that it's mostly designed for defence (specifically what i call passive defence, i.e. AC, saving throws, SR, basically you need to match big numbers to affect him), while at high optimization defence is unfeasible (except active defence, i.e. making yourself untargettable). and at low optimization people try to use it for dps anyway.
i play at middle optimization and i find that monks work pretty well. but as far as fixing them, it would actually depend on the optimization level involved, because monks seem to play a different game than the other classes. everyone else tries to kill his opponent as fast as possible, not to make oneself untouchable.