The illusion is a heavier rated tire is safer.
A safe tire is one that is well maintained and capable of handling the load. Safety is also related to how you drive.
Raising the tire rating only allows more leeway on tire maintenance, my 65 psi D rated tire is still C rated at 50 psi. It does not help with sun damage, axle mis-alignment, poor construction or road hazards.
How much extra capacity you want is a personal choice. Most folks settle on what makes them feel better.
For instance I always have my TT tires balanced because I think it is a good idea. I have never seen any data that it showed it makes any difference.