[MEvang]

First off consider that an unloaded pickup does 80% of it stopping with the front brakes. Any more rear brake pressure can be dangerous causing rear brake lock up.
Then consider that braking is all about turning the kinetic energy of a moving vehicle into heat. This heat then has to be dispensed quickly.
The root problem in the Tundra brake design is likely the size of the rotors. Mainly the thickness and the amount of mass available to dispense heat.
My guess is the engineers where stuck with the rotor at this size and instead went the route of adding more mass to the calipers which also plays a large part in dispensing pad heat. It turn this allowed them to reengineer the pads also.
But not all of the pulsation issue have come from the front. Much has to do with the rear drum which are also low on mass and were not heavy enough. Over adjusting the rear brake or installing them cocked on the axle hub will cause them to warp and transfer a pulsation to the driver.
Toyota also made available a heaver drum which also went into production when the larger caliper did in 03.
Lastly consider that poor repairs habits of technician may cause a lot of problem if the brake design is border line. Poor rotor, drum machining techniques cause more pulsation problems. The problem with the rear drum that I mentioned which can turn up after a rear brake clean and adjust service. Then the fact that many do not torque the wheels properly.
Everything in a brake system needs to be considered as the system work as a hole. Toyota obviously considered the issues with the early Tundra brake when the redesign the new truck. Everything is bigger rotors and calipers and they added rear disc for more loaded stopping power.
Mike