HD truck seat of the pants power was one of the major reasons I purchased my Ford 6.7 PSD. After test driving a '12 ram cummins the seat of the pants feel was worse than my 05 6.0 PSD. I'm sure towing a load that the performance of the two could have been the opposite but driving a truck as a daily driver I didn't want to go with a less performing truck than what I was use to.
Having said that my '12 6.7 PSD has a lot less torque management from any speed than my old 6.0 PSD while meeting even stricter emissions standard in which creates a much more enjoyable truck to drive knowing you have plenty of power in reserve. I agree it has a lot to do with emissions, but having a transmission/drivetrain to back it up is a major factor as well. While pulling my boat I can smoke the tires even better than being solo.