I think the reason for these over-simplified games is because VR is already a very new experience for a lot of people, and events showcasing VR to the general public don't want to add to the learning curve and possible motion sickness by having them play games with complex mechanics.

I had a Samsung Gear VR with which I'd play a Tron-like ping pong game. Lots of fun initially, almost no learning curve, but gets repetitive very quickly.