I think it would be worth carefully documenting the facts for yourself and then, after review, filing a report (try both ATS provider and CHIRP?). This could provide grist for the mill of various safety notices.
I think a root cause may be that VFR or IFR from a pilot perspective doesn't really shift the rules very much (other than the fact you can't be legal and VFR in weather less than VMC and the fact that you need to maintain a minimum height or be visual with the ground - which you should be doing enroute under VFR anyhow). This results in a very casual attitude towards IFR/VFR by a surprising number of IMC/IR pilots.
I am not sure people remember how much higher the vis requirements for VMC are within controlled airspace - and the fact that the VFR pilot is supposed to be visually separating himself from the other traffic.
You can see why controllers so often 'over control' and separate IFR and VFR traffic.