In combined Casevac/SAR unit I flew for there was categorisation of patients. Category A was highest (life or death), so we knew up front what we were facing.
Point to bear in mind: the patient is but one life. The crew was/is three, or four lives if it was a SAR mission. Apart from that, the loss of the aircraft itself might mean that other patients may not be rescued afterwards.
Having first flown helicopters with night vision devices in the late 1970s, (with PNGs, which pre-dated "NVG") I've always been concerned about them being used in circumstances where an IFR reversion/recovery is not possible. I've previously given advice to some via this forum. My advice is that I would not choose to work for an NVG, non IFR capable helicopter unit. Too risky in my book. As an instructor, I helped get RAF rules changed back to something more sensible when new weather limits for NVG operations were introduced which allowed flight in visibility worse than for unaided flight!
These tragic accidents seem to reinforce my point.