Dmace
It definitely makes it easier on the manufacturer. Don't have to stock two different beds, they use the same bed on SRWs and DRWs, just add fenders.
Also, if I get a dually, I would kinda want it to have the slap ons. The commone mishap with duallies is busted fenders, mostly because of being wider than the average truck. While I wouldn't plan on doing it, if it does happen, it is way easier and cheaper to just change the fender.
And another reason for ME to like it, I want. side load toolboxes in my bed, and I would like to get the fenders Rhino lined, because people would be constantly leaning on it to get tools and the like, and in case a tool was dropped on it.
But, I do agree with you, the stamped ones certainly look better IMO. Just personal opinions and uses make the decision I guess.
Kyle