I dont think that has anything to do with it... I really think it is just for looks and wouldnt with stand anything more than a minor rub. has nothing to do with model line there are as many SR5s putting in work on the trails.
You think every car on the road should look exactly the same? That is why there are different models. I like the look of the trail and you like the look of the SR5. That bumper cover is for looks only. However if it did get bashed, it's just a small piece of plastic that can be replaced. Sacrificial cladding if you will.