Not necessarily necessary for VR, obviously, but I remember playing the Re7 demo and thinking how much more immersive it would be if you could handle objects like you would in real life, and is a huge part of what makes VR amazing.
It is, but for me, it begins to get old and in a world like RE7 or Skyrim, I eventually prefer just the immersion of the headset with the comfort of the couch and controller instead of waving my arms around for hours. The cool factor wears off for me quickly with the controllers, even with the Vive.