Tim, it might just be that the blanket "emphatically stating it is illegal and dangerous to use non-certified devices for IFR flight?" Is too emphatic and states a personal viewpoint which is arguably incorrect. Or at least partially in incorrect. As you point out, we do use an EFB (and other non certified equipment) for IFR flight, both legally and to enhance safety. The charts are completely legal and the bells and whistles provided to enhance situational awareness, IMO, enhance flight safety. The suggested callouts are situational awareness items, not primary navigation tools.
As my comments indicate, I share your concerns about an "minimums" callout at minimums, but because I think it does not provide a situational awareness benefit unless a whole bunch of variable conditions need to be addressed and, without them, has too much potential be be dangerous. But that's my opinion on the merits of the specific feature, not some blanket overall idea that EFB are illegal to use in IFR flight.
I think ADS-B weather is a great safety enhancement, but if used tactically rather than strategically, it will kill you. I guess one might argue that it should not be allowed on an EFB for IFR flight. Do you feel that way? I doubt that's the case - I mention it only to point out why others might think your blanket statement that it is illegal is harsh.