It would seem to me that if you could rotate the wing in order to reduce the downward force of the rotor wash which would reduce lift the wing would still develop lift and cause the helicopter to move backwards necessitating the use of forward cyclic. When the helicopter moves through tranlational lift the wing would then have a large amount of drag necessitating the use of a power servo or jackscrew to return the wing to the normal position. This would increase the weight and the complexity of the aircraft systems. I may be wrong but the only operational helicopters that have wings are gun ships and most of the time they are using their offensive weapons while flying and when the use these weapons while at the hover they have no problem due to the amount of installed power.
Depending on the helicopter design the wings are installed to allow reduced collective in forward flight by offsetting the lift required from the main rotor. Most helicopters that have wings enjoy this same feature but the main reason for the wings is to hang things from such as weapons, fuel tanks and supporting electronic systems.
Maybe Nick can tell us if the weapons supporting system on the UH-60 generates any lift in flight and what the penalties are while in a hover.