There is a limit to how much originality 'one' could create. I've always argued that their are only 'so many ways' to tell a love story or revenge story, etc. sooner or later, structurally you'll encounter similarities in structure, layout, tone, character behaviour and themes. Let's apply this concept to something Destiny related. For example, let's pick a weapon. What are the defining concepts of a hand cannon. Once you've identified those universal parts and incorporated them into your design you'll find that your base model will have certain uniform design characteristics. From there you'd find that there is only so much you can do with the basic design. Bungie seems to have prioritised original design for its exotics. In the House of Wolves however they have gotten better at making their Legendary weapons stand apart from the common, uncommon and rare variants.

Go watch grandma's boy....the answer is in there

Do you know the difference between models and textures?

You do realize that the majority of HoW weapons are new models, right? A few of the crucible drops are the same, but that's it.