I remember it being a Bungie-era consideration that they talked about at one point. It kind of highlights the importance of such for multiplayer and identifying weapons at all sorts of angles during gameplay, and that's also where colour schemes help as well. In Halo 4, they made the colouring of the new plasma rifle and carbine so similar (dark blue), it's just silly.
Note how 343i must use a separate UI outline on items in-game. It's incredibly distracting, but I find it's just a hack on top of a failure of gameplay design considerations.
Note how 343i must use a separate UI outline on items in-game. It's incredibly distracting, but I find it's just a hack on top of a failure of gameplay design considerations.