I'm not sure if I've missed the point here but speaking as an ex-controller I wonder if a couple of different concepts are getting confused here. If you are talking about flying in the vicinity of or approaching an aerodrome the meteorological conditions are a bit of a red herring. Bear in mind that outside CAS a fixed wing aircraft may quite legitimately fly at or below 3,000 feet amsl without maintaining 'VMC' vertical and lateral distances from cloud provided that it remains clear of cloud and keeps the surface in sight. Similarly, inside CAS a fixed wing aircraft flying at an IAS of 140 kts or less only has to stay clear of cloud and in sight of the surface. So making the distinction between VMC or IMC doesn't really guarantee that there will not be any other aircraft around. Outside CAS, of course, ATC may not even know the other aircraft is there as Cruise experienced.
Whilst I claim no knowledge of flying anything but spamcans it seems to me that a rule that says 'operate aircraft in a manner that can establish that the intended flight path is clear of other traffic' caters for any situation (goal-based as the rulemakers call it) and gives the crew an appropriate environment to avoid collisions. To me it means clear of cloud and in enough visibility to take avoiding action in a timely manner if it is necessary. I'm not sure how you can say that you are operating the aircraft in a manner that can establish that the intended flight path is clear of other traffic if, when you pop out of a wee bit of cloud you decided to go through, you might meet another aircraft.