Another one of the things we miss in desk flying is just how much physical effort it takes to fly and/or fight with an airplane
I have OR DK2 and i only tried it with DCS. After having one dogfight i was breathing like if i was running for that time. I was moving around like crazy, twisting my entire torso in all directions to keep the visual at all times. Sometimes i would turn so much that i can barely (tips of my fingers) hold my hands on stick and throttle. I gave up flying with DK2 because frequent fps dipping under 75 gives me nausea that i can not shake off for hours after that.
As far as not seeing the keyboard and stuff… when i mount OR on my head, there is a little hole around my nose that i look through and see everything. For flight sims where you have many buttons to press in your real (home) simulator, they are coming out with some hand sensors and other additional stuff you can buy. I guess people will be able to see virtual hands and you will not need to see mouse or keyboard any more.