Why apply the limitations of the technology of today to shoot down an idea for tomorrow?
It would be very depressing if everyone had this mindset, and nobody at least tried to figure out how tools could be made to enable creation of models rather than just visualisation.
"You can't move past your walls in VR, locomotion is impossible, until we develop force fields and antigravity it just won't work" wasn't what people said. Instead they are using teleportation now, and who knows what is next.
Maybe for now, we restrict model creation to 'basic' shapes because of the resolution. Like Tilt-Brush, many tools are at your disposal. For fine control, you select a plane and then use the touch pad to incrementally scroll co-ordinates. maybe new intelligent snapping algorithms based on head view position etc.
Who knows, this all may end up to be a terrible idea. But as a community people should at least try first.