Unfortunately it's just not possible to achieve this at the moment. The relationship back to the Incident object isn't created until the collection object is saved so there's no way of obtaining this data for display, not even using a calculation.
I think it's a brilliant idea though so it's well worth submitting a suggestion to your Support provider.
Does anyone know if this is still the case or can this now be achieved in 7.5?
No not 7.5 SP1, and I've not heard that its in 7.6 either.