To me it's very interesting the number of folks that are trashing the dealer and Keystone when the OP hasn't even heard back from Keystone since he only contacted them last friday.
From the looks of the damage,I'll bet that it was okay when he inspected it and somewhere between the dealer and delivery,1900 miles(?), it may have hit a stretch of rough road,or a curb, and it overstressed an already poor piece of wood. I'm betting that Keystone comes through for the OP as they did for me on a TT with wiring that got pinched and could have caused a fire.
When you look at the materials used,pine is light and soft,Fir is a little more costly but harder and oak would be the best in hardness but the highest in cost. The other thing is that can you imagine how much these trailers would weigh if they used all 2x4s instead of 1x4s? We'd all be using 1 ton pickups.