IMO...
'P' rated tires are for light use. Sidewalls are too soft for towing, You can feel the sidewalls flex, when you go into a curve even when you aren't towing.
'D' rated tires have a stiffer sidewall 'D's are better for use on trucks than 'Ps'.
'E' rated tires have an even stiffer sidewall. Very little flex.
'E' works well 4 wheeling and towing.
I tow a heavier trailer, and find the 'E' rated tires hard to beat.
Downside to 'D' and 'E' rated tires is they may weight 20-30# more per tire. A little reduction in MPG.
Lastly... You get fewer flat tires with a stiffer tougher tire.
Just my experience.
If you use your truck like a 'Grocery Getter' and don't do much off road driving, or if the heaviest trailer you tow is a 5X8 utility trailer with a lawn mower, there is less need for stronger tires.
Lots of people are content with a 'P' rated tire.