I think that's definitely true for non cockpit based games, but games like Dirt Rally, Pcars, Eve Valkyrie etc are every bit as immersive when using the appropriate wheel/joystick. I've been playing all 3 non stop this week with a Fanatec clubsport wheel setup and Saitek x52 for Valkyrie, with dual butt kickers on my chair and Simvibe handling vibrations, and I can assure you that it's vastly more immersive than just a 3d screen around you. Motion controls would quite honestly be inferior for cockpit based games. Dirt Rally with a quality wheel and seat vibrations is the most immersive video gaming I've ever experienced at home by a long shot. I definitely still want my motion controllers, but there are plenty of games that will give you an incredibly immersive feeling without them.
At this point you could already build a real cockpit and use screens for the windows instead of the HMD. But this is not the regular out of the box experience you get with VR.