I get where you're coming from. I may **** with my motors and build power with them but I always run as much of the emissions equip as I can. For me, my dog, and everyone behind me.
That said. US air quality has improved dramatically since the 70s. When manufacturers come and tell me they cannot make or sell me the product I want (truck with a manual) because that one particular option pollutes too much, I will get very pissed at this. I'm not even asking for diesel at this point. If someone drops a brand-new 2020 Gas truck that shifts with a stick I'd be first in line with my banker ready to buy it. But no, they emit too much.?
You mention the modern diesel trucks at 1000+ ft-lb torque being cleaner than the models before. This is very true, especially the new DEF systems. Is that fully because of the auto trans? No... Or is the engine capable of meeting emissions, but the manufacturer unwilling to sell one that meets a greater fuel economy standard?
Strict Federal standards for new vehicles are fine. My state does not run emissions tests anymore so I'm fine. But for the love of all that is good, don't pee down my neck and tell me it's raining. What isn't fine is telling me that choosing what gear my rig is in is bad and that I can't do it. These are dark times for those that like to row their own. I will buy dirty, sooty, oil-slobbering old trucks with a manual transmission before I buy a new one without.