When I get into my car I put my iPhone into the console. Others put it into a holder on the dash to use it as navigator. The few times I have had to pull it out of my pocket, I can't say there has been so much force it would bend so easily!
?? pulling it out of you pocket with so much force it would bend would not be normal usage.
Normal usage for the plus would be different than normal usage for the 5/5s due to the size alone.
I don't think people are taking that into consideration when defining normal usage IMO.