I'd point out that if unauthorized affiliation is such a safety hazard, and if people are going to keep buying surplus radios of eBay, then system owners should demand Motorola to make it easy to do NAS. AFAIK, it's mainly a Motorola issue, as Harris and BK can be set up far easier.
Scanners are going to exist, so people aren't hearing anything they couldn't otherwise. Call it harm reduction.
Perhaps the real issue is it defeats the ability of Motorola to sell you expensive stuff, like advanced system keys, KVLs and KMFs, and monitoring services, to fix a problem they created.