The problem with flying IFR approaches in VMC outside CAS is that, if you're on your own head-down on the dials, no-one is looking out to spot other aircraft and take the relevant 'see and avoid' action in accordance with Rules of the Air. Although if you're using a decent autopilot, it'd be a different matter, of course. But in reality, the rule regarding 'practice instrument approaches' would be impossible to enforce
But that goes whether you are IFR and flying a "real" approach (in VMC) or VFR and flying a "practice" approach.