MacRumors:

With the wide display option, there’s enough screen real estate to use four apps at once without compromising on window size. Ultrawide bumps up the available space even more, and it’s almost too much display space.

Using the ultrawide setting is like having multiple curved Mac displays in front of you to handle your Mac apps, and then you can also add in visionOS apps to better utilize the virtual space around you. The larger screen sizes for the Mac do improve productivity because there’s so much more space to work with.

Note that you still can’t use multiple Mac windows when mirroring your Mac display to your Vision Pro, but the wide and ultrawide provide so much space that it’s essentially the same function. Apple says that the ultrawide mode is equivalent to using two 4K monitors side by side.

If this suits your physical workspace (like, say, if you live and work in a studio apartment) or travel needs, it comes close to justifying the cost of a Vision Pro by itself. A single Studio Display costs $1,600 (without a nicer stand, without the nicer nano-texture coating).