Well, someone way back when thought they were special.
I'm like you guys, but I think it's normally a self-correcting problem. Predators can see them very well, so they don't generally live to long in the wild.
Considering that these deer have been in an enclosure for at least 45-50 years (see my post above), I'd say they aren't endangering the general gene pool of that area. Considering that they're still alive, breeding, and apparently healthy, then I'd say they aren't much of an issue.
If they had diseases that could be passed through the fence, then that'd be a different story.
They're sort of unique, so appreciate them for what they are. I'm not one to advocate killing what I see as fairly tame deer that were raised in an enclosure, simply because they're white.
If found in the wild, and they're in season, I'd shoot one as quick as any other deer, but that's really not the issue in this case.
Daryl