The current look seems to come directly from an artist's impression, featured by NASA: https://www.nasa.gov/mission_pages/WISE/news/wise20110823.html
Given that, I'm not too bothered by the overall look of them, especially since Elite's cockpits seem to have an "ambient light correction" feature, as evidenced by the brightening of dark sides of planets.
Of course, that's also a bit over done, in my opinion - dark sides and Y-class dwarfs could do with some dimming of the ambient light... but at least FDev is fairly consistent in how they handle low light environments.
That's reflected light (the look of the artists impression). Not emitted. stars at the temperature "of the human body" dont emit any visible light.
I have no problem if they wanna make Y-Dwarfs look purple if they're in a situation where they're lighted by an object actually emitting light. If they're not though, they would be dark and should be dark because it adds to the game