Yea I think your overthinking it or you haven't orientated yourself to the operation of the truck very well. As soon as I get in my GM HD with a trailer hooked up, I push in the tow/haul and I hit the exhaust brake switch before I even put it in gear. I then as I pull away with a load I set the adjustment with the left hand on the brake gain. I pull often enough that in dry conditions based on what trailer I have on and how much weight is on the trailer I know what number to set it at. All of that is done at no speed or low speed. When I am driving at speed, there is not typically any emergency actions to take as far as activating switches or adjusting brakes. If the brakes do need to be adjusted (sometimes necessary during the Winter, it is done with the left hand and only takes a second or two. If you running it in manual than the gear selection is done with my right thumb with right hand on shift handle. Honestly since my 2015 and now with the 18, I have never used manual. Use it often in my 06 and other D/A's but have not needed it on the newer trucks.
As for the interior on the new Medium duties, I dont find it dated. My expectations in those trucks is much different, at least for me. Extreme durability is my biggest expectation. Ergonomics is next and lastly visual appeal. My interior on my GMC 05-5500 4X4 was poor, way too much light duty plastic, ergonomics were good, everything that mattered could be actuated with gloves on. However the quality/durability was not where it should have been for a med. duty truck. It rattled from day one. Plastic pieces broke, seat was not great either. I was really hoping for an update. Turned out I got one, 10 years later but looks like they are here.
The fact that they are using the same GM cab is actually a comfort for me. It should be as tight as the HD GM pickups and I never had issues with the interior falling apart on those trucks, but if it can be broke, it will in a medium duty truck in a commercial application.
