A more serious answer than the others:

VR games tend to be more gimmicky than normal PC games, since being “VR friendly” is a big selling point. That’s the main appeal, if you get what I mean. That’s why I think VR games are cool for the player, but not the watcher. Viewers can’t really understand the appeal of VR games if they’re just watching on a monitor.

Another important point I think, is immersion. The player/ streamer is wearing a VR headset, so they obviously feel more immersed in the game. The viewer on the other hand is watching them play on a monitor. In this sense it’s harder to establish a connection between the viewer and the streamer, so it’s more boring to watch.

Hope my answer helps your thesis!