I think the problem lies in your intimation that being someone else for a time is not alright. People that are unhappy with who they are may chose cosplay as a method of escape, just as they may chose alcohol, or painting, or music, or any of a variety of methods, good and bad, to 'lose themselves'. Creative expression, recreation, novelty, fun - these are also reasons people chose cosplay; it is not a prerequisite that you have problems.
You may feel their potential may be better used elsewhere, but as much effort might be wasted by people chosing how they apply their own talents, I feel that to do otherwise would incur a cost beyond any possible gain.