I can agree with Pirouette entirely on this matter. Rawlith-Dar and Varnadiir are hunters just as much or even more so then Bjorn, but their armor is ultimately armor. Rawlith-Dar uses Bonemold formed using Mammoth Bone rather then the remains of the typical Morrowind Crab shells that are left from their extinction. Varnadiir uses Guild Armor from his past, there roles don't definitively define their gear, but it influences it. 

They will both be getting more personalized, more advanced gear much later on in the story, but for now they retain, simple, realistic, armor designs for their use.

 One a sub-note. Dragon bones retain no magical quality, they are merely such a dense rare, hard to use material that it is essentially pointless to try unless you are a smithing God among men. Secondly, Dragon Bones haven't even thought of being a resource as they aren't present aside from a singular preserved skull inside Dragonsreach. There is not only an immense amount of skill required that he could not gain from them being present, but even when they do it would take him another decade or two to even get good at smithing with them.