The biggest issue preventing that is that to do better than your dual 4k monitors the VR goggles will have to have many more pixels on the much smaller screens, which is hard to do reliably from a manufacturing standpoint and would require an enormous amount of processing power to render at the 90FPS that VR requires to be comfortable.

Would it need more pixels if all it is doing is scrolling up and down a virtual monitor though?

If you want to see more on the screen at any one time than your current 4k screen it's going to require more pixels no matter how you arrange everything else. If you want to put it 'deeper' into the VR world than just placing the exact same screen data onto the VR screens will require multiple real pixels per fake VR screen pixels.

Also don't forget you have to have 2x panels with the increased resolution at smaller sizes than the existing monitors.

Finally if you are just scrolling through a virtual screen there's no reason that can't be done on today's monitors and we already have eye tracking tech available without having to jam that tracking into already crowded glasses.

I am willing to accept tradeoffs in resolution for more working area.

I basically have the equivalent of 8 1080p monitors, but if I can get the equivalent of more 1080p monitors over a larger area but at a lower pixel density (downscaling is ok provided I can zoom in and out), I'd be totally good with that.

Almost every article and demo I've read and watched about AR in the last couple of years mentions huge virtual screens everywhere. It's in all the Hololens demos, for example.

I haven't seen any examples where the entire field of view is basically a giant Windows or Mac desktop, which is what I'm talking about. Most of the stuff I've seen are just like the video linked in the parent thread.