Well, I am a little bit of a control freak and simply don't want to have to deal with others while I make my sim worlds. So multiplayer is off the table.
Also I don't see VR being great for the sims, I see it being useful for RPG games, where you are one character and exploring a world (basically it lets you be a character/you are the character), in the sims I like building my own worlds and playing multiple people (You are not being a character).
Also as someone mentioned VR makes a lot of people motion sick that I know. When I was using it I was fine, but most people in my family didn't do very well, so I could see it being annoying if it didn't also play normally.
Open sandbox wins because I play the sims to create. That sandbox is the most important part of the sims for me, if it wasn't for the sandbox I would not be playing the sims.
