To each their own but if you look at the majority of Jeeps that are doing serious rock crawling will disagree with you, it`s not a matter of stiffness depending on the manufacture it is about the construction of the tire and the E range having a different material or process to prevent puncture from rocks. Like I said to each their own even as far down to what tire pressure suites them best. I have used Tire Talc and chalk to see just how much contact area I had at different psi. I have run C,D, And E range tires on my Jeeps, JK, JL and with the E range deflated down on both the front and rear driving down the highway it was hard for me to tell the difference between the 315/70/17 C (35) And the 35X12.50X17 (E) range. If you ran them in the upper 30 psi I would say you would notice the difference. This is just my opinion, everything comes into play with this from temperature, shocks, vehicle weight and distribution, road construction weather pavement or concrete etc. and don`t forget maximum MPG`sI don't necessarily agree with your assessment. Typically load range C tires will allow your tire to air down more effectively, giving both a better contact patch and allowing the sidewall to flex better and wrap around the hard obstacle, which can often prevent sidewall puncture at least as well or better than a stiffer sidewall. Thickness is not always a true indicator of strength or puncture resistance.
I know of a lot of people on the Raptor forum will not change to a d or E rated tire because Ford worked BFG in designing a C range tire for that truck and it`s suspension. Bottom line is you have to find the combo that works for you depending on what you are using it for. And if you called Tire Rack and spoke to two different salespeople you might just get two different opinions right from the start