Fuji, you have hit the nail on the head. The airlines can't justify anything because the IMCR has a great safety record for a number of reasons. The holder of an IMC is split into a number of factions. Those that do it as a way of improving skills but have no aptitude or desire for instrument flight.
Those that do it and see it as a get out of jail free card but in reality never actually fly near iMC conditions or even in aircraft that are remotely IMC capable but like having the 'badge' that they are 'instrument' pilots.
Then there are the IMR holders who view it as a serious instrument qualification and spend considerable time, effort and money in consistently improving those instrument skills. I flew for more than a thousand hours using the IMCR.
The final group are the FAA IR holders who have an IMCR on the back of an IR. Again they have proven their dedication to safe instrument flight by making the effort to go out and get an ICAO IR even if 90% of them can't exercise the privileges to the full extent.
So if you look at the typical use of the IMCR the stats stack up very much in our favour.
The big problem in these discussions is that the people are incapable of separating a proper IR (FAA or JAA)from the IMC and the view that the IMCR is as good as an FAA IR and getting the FAA IR is just a top up. i have met very few IMCR pilots who were capable of doing any IR in minima based on their IMC skills. Those that did came from the regular IMC flyer group as mentioned above which in real terms also puts them far above minima as well. I did my JAA IR in exactly the minima including a first pass on the test, was that as a result of a mere 15 hrs of IMCR training or a thousand hours as an IMCR pilot?