I think it was a late idea and rushed through design and production. Also, the costs for sourcing a proto and then a full production run aren't inconsiderable either, so I can understand wanting to find the balance between rice paper and crayon vs mil grade impact armored lol.
That being said, I think there's an excellent opportunity here for a mechanical engineer to make a heck of a product, make sure you go through channels and acquire proper licensing from Bethesda first, but I like to think if you sweetened the pot heavily in their favor, you could still make out like a bandit for producing the 'indestructible pip boy 3002' or as close as we're going to get in this lifetime.... but just being the guy with a really nice design with better materials, why wouldn't Bethesda let you make them more money? AND increase the happiness level of their 'customers' (instead of settlers, but I like to think they're watching and checking reports like we do now for our settlers lol)