You know, after I posted that screenshot, I figured it would answer the holstering question. It appears I am wrong, and the fan community will remain unsatisfied until the player is offered settings to individually customize each weapon's "ready" carry elevation, angle, and cant... and given customizable holsters with which to stow their firearm. Well yes. Since you are staring at the same gun for dozens of hours on end, it's as large a factor as the HUD. Especially since it can block a tremendous amount of visibility. I don't see why this shouldn't get a little attention. Plus this is a feature that has been added to countless games. And in mission I am not sure people would want to holster their weapon to talk to their companions for a second or walk towards an interactive element. So hopefully the devs consider inclusion before launch.
One of the issues that I have, and many more do, is that as you wander around, you are constantly aiming your gun at shop keepers, companions, and the like which is extremely immersion breaking. I hope that in this game you can ask the programmers to take a moment and insert a little code and animation to lower the gun when you aren't aiming down sights or no hostiles are in the area. Thank you for considering the request, I look forward to the day I can pre-order, and thank you guys for making memorable character driven games.