At least as far as fiberglass goes, they did a good job of making it thick, but yeah, something stronger would seem more appropriate.
Regarding the front, its actually pretty thin and ill supported to keep from bending as i've found after hitting somebody who ran a light, but better than nothing for sure. Ofcourse in comparison to the frames of most vehicles the bumper doesn't look much thinner, but it's a noodle compared to our frames. I think the thickness of our frames makes it a uniquely well suited vehicle to heavy duty aftermarket bumpers becuase you're no where near the risk of frame bending like on toyota's and jeeps.
I wish they had found a way to keep it more like what i have now (the tow pin bumper from earlier 463 model years) which may be a little thicker steel (although not a whole lot compared to my rear bumper), but it's reinforced and box sectioned from end to end much better than the current stock bumper... it seems like a strange direction to take the design since it often has a tranny cooler right behind it.