Mr. Lappos, I understand your post and I know what a WAAS approach looks like, I flew a WAAS capable Bell 430 until last September, ironically in EMS, because the program and the company believed IFR was (I concur fully) the solution for a safe operation in EMS.
The spirit of my reply was directed towards those 135 operators (ironically Saturday night crash was one of those low cost operations) that refuse to spend the money to improve their safety record.
However, it must be mentioned that any type of precision approach would have not saved that crew.
Three main points for EMS:
1) IFR, with a developed network of WX reporting stations (AWOS3, ASOS) at any location where an EMS helicopter is based.
2) WAAS GPS Approaches at those locations and rural helipads.
3) Helicopters performance sufficient to carry at least one patient and the fuel to fly IFR to an alternate.
Those would be mandatory.
Further measures.
Draconian control over anyone who knowingly busts WX minimums, that include pressure on the part of the customer (the hospital).
ACTIVE, not database fed EGPWS systems and obstacle warning systems good enough to detect power lines.
If they want to play they need to play right.
I can tell you that the costs involved shall pale compared to a legal settling after three lives are lost.