Going back to the locked threads and comments by Karl Lang. He's always proposed that there be a bit of white in the soft proof surround with paper white simulation, which would aid in users not perceiving the image being 'too bright' such that we don't end up with 'prints that are too dark'. We see this to some degree in Lightroom when invoking a soft proof. It's an off white and it gradually (although not slow enough) fades in. LR's dark interface aids too but any menu's or other GUI elements that are white (as white as the display is currently calibrated for, not the paper white simulation) can cause visual issues here.
Bruce Fraser used to recommend that when soft proofing or for critical viewing, hide all Photoshop palettes and move into full screen mode. The issue with PS then and today is when you turn on soft proofing with the paper white simulation, it isn't gradual and you get the visual effect of what Jeff Schewe called the "make my images look like crap button". Bruce recommended one turn their head away, invoke the soft proof with paper white simulation and full screen mode [size=78%]via the keyboard[/size][size=78%], then look back so you don't see the preview update. The appearance doesn't look anywhere as bad as when you watch your (perhaps) 1200:1 contrast ratio display, with white being as white as it's setting for the UI instantly change on screen to the more appropriate and ideally 'correct' soft proof preview. So LR is moving in the right direction here, noting has changed within Photoshop. [/size]