The NCR circle on wm, instead of green, could be red for members of faction that have bad karma there at least.
But I still with first point: This thing must end.
I would agree that it shouldn't be green, but marked orange like any other unsafe town (why would it be marked red? It isn't a dungeon). Not to protect fools who can't be bothered to tell their own members that Shady Sands guards will shoot them on sight, but because new players in particular are susceptible to the usual tricks to kill them to take their belongings. Though maybe UV players need a necro-like prompt before entering: "You are about to enter a most dangerous place...BOO!"
When NCR was enemies with the Brotherhood of Steel, the guards of the BoS bunker location (marked green no less!) would fire on NCR players who entered. All new and existing NCR players were informed that BoS was an unsafe location, No whining, no crying, just choices and the consequences of such based on relations between the two factions. If you can't manage to tell your guys the same, then you're incompetent.