Do you have any idea how complicated this would actually be to implement? This isn't just a matter of adding VR support or changing the camera to first-person. You're essentially asking for an entirely new game built on top of The Sims 4.
The game would need a completely different player perspective and interaction system, human-scale environments, VR movement and controls, physical interaction with Sims and objects, appropriate animations, collision and physics systems, haptic integration, and a whole new way for the player to interact with the existing simulation.
At that point, you might as well be asking them to develop an entirely separate game rather than simply adding an "immersive mode" to The Sims 4.