The K1600 has been around for 10 years now and was designed for Euro3. The 2017 facelift model was tweaked for Euro4 and they have made it very smooth which some like and some don't. I have had four Euro3 K16GTs and to Euro4, and the Euro4s have definitely lost something if you are after the sporty side of the bike, the first 5/10% of the throttle now does nothing, and 85% twist only give 50% throttle, and Dynamic mode is now really tame compared to the Euro3 model. I have had my throttle maps tweaked to make it more direct which I love, and if you look at the Bren Tuning website they have an ECU flash that basically puts the Euro3 throttle maps into a Euro4 ECU.
I am sure if it got through Euro5 they would have done it, but like a lot of older designs it was probably a step too far