This may sound biased considering I am a dev but I'd like to offer my own experience:

At first I thought VR was fairly gimmicky while I was developing with DK1-2 for several years. As a kid I had loved the few and far between VR demos in the 90s I got to try but I became very jaded about the possibility of anything turning VR around. Even after going to valve and trying early versions of the Vive and being able to see my hands/body in VR with IMU suits, I knew it was cool but I was unconvinced that it would succeed as a consumer product until two things happened...

The first was that I saw the virtual real porn clip - goodmorning II. This was the first clip where they had managed to get the IPD for the cameras correct and the scale of everything was perfect. Instantly you go from "Haha virtual reality 3d porn of course that is going to be popular" to "holy fuck, this works too well people will buy this shit religiously."

The second thing that happened was a bit slower over time effect on me. I really hate the words presence and immersion. Everyone wants to pretend they're being transported away to magical worlds, but again my jaded pessimism glooms through and I will always be aware that I am playing a video game, not living in another universe. However over time as I develop content I've come to see the stuff I create as much more real, and I care significantly more about the physicality and existence of things in VR.

TLDR; I wouldn't buy dlc or characters or extra content for a normal game, but I will in a heartbeat for VR. Also as everyone else will say, regular games have slowly started to disinterest me.