Mission Adaptive Wing

I remember reading a years ago about work being done to develop the Mission Adaptive Wing (MAW) w/c would allow an aircraft wing to change its shape as needed to suit the mission it was tasked to do. This would allow an aircraft to excel in all flight regimes, from low subsonic to high supersonic speeds and would help create a truely effective multimission platform. I thought this was a great idea at the time but strangely, no actual aircraft since then seem to have capitalized on this technology. Anybody care to speculate why?