Indeed, headbob is one of the worst things in video games. First, it's sickening (mismatch between your equilibrium organ and bobbing eyes - not to be mixed up with sitting in RL in moving car/train and watching the evironment). Second, IT IS TOTALLY UNREALISTIC AND STUPID.
When you walk (run, jump or whatever) in the real world, the world also does NOT shake in front of your eyes (unless you sit on an old washing machine with a high spin cycle). The world in front of your eyes is always fixed but your eyes slide in front of the scenery (don't know how to describe it). Do you have a feeling of the world bobbing up and down when you jum rope? No. You still perceive a "fixed/immobile" world but your eyes are moving (along with your body/head).
In a video game the screen level itself are your eyes. The player's eyes don't exist within the video game, so to speak. When the screen level shakes (head bob), it creates an effect that does not exist in the real world. Since your RL-eyes are a second level in front of your VR-eyes (screen), you perceive a shaking world instead of moving eyes/body in a "fixed" world.
So in short, make head bob optional and everybody should be fine.