The point being simulated instrument flight in VMC - not flight under IFR in VMC.
If you are flying in VMC outside CAS, there's a chance that someone else will be flying VFR nearby. In VMC you must observe the Rules of the Air regarding collision avoidance / right of way. So, if you're head down following the dials in VMC, someone else must be there to look out for traffic which is expecting you to give way, but which you won't see yourself....