There is far more to it than stepping on the brakes in your car.
While shifting is indeed a subconscious action to a competent rider what we are attempting to focus on is the band width it takes when riding a challenging technical road. Our brains are doing hundreds of calculations per second gauging the vanishing point, road surface, entry speed, line, apex point, etc., what gear when and how, while taking in sensory data from inner ear, hands, knees, butt, feet as to what the bike is doing in response to braking, turning, accelerating forces. What gear to be in, when to choose that gear, how to upshift or downshift into and during the turn takes a lot of brain power that could be doing something else or doing something else better. DCT eases the workload allowing the rider to concentrate on line and speed selection. The result is a safer, higher performing rider. DCT also allows gear shifting in corners that does not upset the suspension which is something most riders do not do at all or do not do well.
A really good book on the brain and how it operates a motorcycle better is The Upper Half Of The Motorcycle by Bernt Spiegel. It's a book on improving your riding through understanding how we subconsciously become a single entity with the bike. Yes, we want it to be reflex and without upper brain involvement.
