It's extremely difficult to accurately hit buttons floating in free space with any type of speed or consistency. By anchoring virtual buttons to your physical

It's extremely difficult to accurately hit buttons floating in free space with any type of speed or consistency. By anchoring virtual buttons to your physical hand, your proprioception kicks in and you can rapidly and accurately hit keys. It's pretty much trivial for most humans to tap the same spot on their palm without even looking, but most people can't do this with an arbitrary spot in free air. The VR/XR industry has tried floating virtual keyboard many times in basically every form you can imagine. All attempts have been abandoned because they suck really bad. This is an idea that is fundamentally incompatible with human psychology and physiology.