This is true. Many of my neighbors crawl over the speed bumps in their 4x4 trucks & SUVs, while I take my little Ranger over them at 15 mph. Won't hurt an F150 to go that fast, or more, but not here . . .
I have one aluminum vehicle (see avatar), and have no desire to drive one down the road every day. I don't always use my truck as a truck, but I do haul yard waste, firewood, topsoil, manure, gravel, bulky items, lumber, etc., periodically. Just Harry Homeowner stuff, really. It would be like keeping my plane outside and abusing it it every time I fly.
Just don't see the aluminum rears lasting 10+ years like my steel ones have (first truck sold at 14 years, second (small) truck going strong at 12, no plan to replace soon).
How does Ford protect against corrosion, both environmental and dissimilar metals? You know, aluminum bed to steel frame? Steel bolts through the aluminum bed surface? Spare tire hanger under the aluminum bed? It just moves the corrosion to use aluminum bolts for this, besides the need for more and larger aluminum bolts.
No thank you!! Ford can keep their aluminum truck beds, I sure don't want one.