I refuse to believe you cannot improve reaction time and that it is based on genetics. There is nothing that cannot be improved, we are talking about muscles and neural connections. The skill to be learned to increase reaction time is how to let go consciously of what you are doing, a mental state athletes refer to as "In the Zone" Recent studies have shown that the subconscious mind has made up it's mind on what decision you with make up to six seconds before you make the so called decision with your conscious mind, so the better mastery you have of technique, and the more you have faced a certain situation, the quicker your subconscious can make that decision and the quicker it will do it for you. Pros make these amazing quick reflexes because they have trained more, trained smarter, and been it the situations thousands of times, Desk can play on two sticks at the same time because he has endless hours of practice, and trained himself to do completely separate things by playing two handed tap bass guitar for so many years.Most important is reflexes. Followed by knowledge, matchup experience and finally the ability to read your opponent.
The last 3 are intrinsically linked and excelling at 1 or more of them is enough to see you past most decent mid level players. But you cant increase reaction time, its genetic. and when you play a daigo, wong or hart in person you will see how much faster their hands react than yours and realise why thwy do so well.