I don't personally see how it's not a gimmick, just like 3DS style "3D gaming" is/was a gimmick. All of the VR games I've seen look and feel worse than regular gaming. I can appreciate if some people like it. But VR gaming, to me, does just feel like another gimmick. It presents you this illusion that "oh look, I'm IN the game". But I know I'm not in the game. And it doesn't FEEL like I'm in the game. It really, to me personally, doesn't add anything to make the gameplay experience more "immersive".
If anything, much like the "3D" in 3D movies or games, it takes me OUT of the immersion, it reminds me that "yup, you're playing a game that wants you to feel like you're in the game". And To me, I'm good. I don't need or want gimmicks, including motion controls, which also really didn't feel more "immersive" (half the the time controls wouldn't always even work properly). I'm the gamer that just wants to sit down, with a controller in my hands, look at a TV screen, and play a game. No frills, no gimmicks, just the game, and me.