We use Virtual Reality because of its immersive properties. The reason why VR is much more effective, impressive and “realistic” than regular good old 2D flat screens is because of the fact that it is an ambient experience. The visual sensory input we receive through our optical detectors, a.k.a. eyes, is present all around us in 360 degrees.
In other words, our experience of physical reality is also ambient just like VR. Recently developed high quality Head Mount Displays (HMDs) mimic this property with stunningly high resolution and low latency. As a result, they convince our brain in the authenticity of the experience, at least in terms of one of the sensory inputs that we receive.
The following quote from the co-founder of Wired magazine Kevin Kelly explains this point perfectly
This is the real transformative power of Virtual Reality.