The report regarding the Hudson river collision is pretty defining. Basically says the controllers can't watch you all the time (happened in RADAR controlled airspace) and if they had proper training and had heeded the conflict warnings from their own systems it would have been a different outcome. The floatplane collision was another where one aircraft had its altitude readout 'switched off', had it been on, the other aircraft would have received an aural and visual alert to the conflict.
The technology is more than capable of saving lives, however the persistence with RADAR controllers and see and avoid being 'enough' works against it's proper use.
As for rejigging CTAFs for radio broadcasting changes, it's moving deck chairs on the Titanic. In Alaska they tried the multicom thing, combined frequencies, so on, and found no real reduction in the rate of Midairs in high traffic zone (16 since 2005, 4 more since the CTAF changes in 2014). Suprise, suprise, the big finding is if you don't mandate calls, most don't talk, and if no one talks and you rely on see and avoid, they hit each other.
WRT to JQF vs AEM, if only one of those aircraft had a CDTI the incident would most likely not have happened as at least one of the pilots would have been alerted to proximity.