Main reason: so I don't have to sit there wearing my HMD just to watch the glacial progress of a track loading. Needs: a status window, at its simplest just text showing the track loading % but could also show session progress (e.g. if for some reason you're not taking part in the race, because you've crashed out or it's a multi-driver event) or other information.
Maybe i dont understand your suggestion but the track loading screen is also showing on the monitor when not wearing the headset. This was introduced some months ago. Only when sitting in car you have only the VR view