Outside of the acceleration improvement DCT's offer something that often gets forgotten is that it's expensive and difficult to manufacture manual transmissions for high horsepower cars and still retain smooth shifting people are used to on cars like Civics. Look at all the GT500's and Corvette owner complaints about the Tremec transmissions being balky and grinding. The Ford/Getrag 6-speed for the 420 hp Mustang is a frequent source of complaint from Mustang owners compared to automatic owners.
Having all the power of the GTR with AWD traction I imagine a lot of owners would destroy manual transmissions and fry their clutches after a couple of launches. Manual transmissions really haven't progressed as fast as automatics and DCT's. A lot of them wether it be in a Mustang, Genesis Coup, 370Z, EVO, or whatever still suck and the problem is that engines are making more power and torque all the time making it easier to shift to DCT's that can be programmed to maintain performance and reliability.