Would this have something to do with pressure from Cirrus/Garmin?
When the Cirrus first came out with the glass cockpit based on the G-1000, I believe they could not get the combination certified for IFR airways (in the UK only) because of the UK-only requirement to carry an ADF. So they had to put a 19th century ADF in an otherwise 21st century cockpit. And, obviously, none of the drivers actually used the ADF, possibly except for training, because it wasn't integrated with the G-1000 like the other NAV instruments (GPS, VOR, ILS, DME, marker). Very expensive ballast. I have no doubt that Cirrus and the other a/c manufacturers that use the G-1000 (or any of its competitors), plus the drivers of these machines, do not regret seeing the requirement disappear.
I would also imagine that the law says something like you can only plan and execute a flight for which you are suitably equipped. So if the planned flight ends in IMC, at an airport which only has an NDB approach, then, by law, for that flight you need an ADF anyway - or make a different plan. Nothing new there really.
As for using NDBs enroute: yes, it's a shame that they are disappearing, but we GA have to remember that we are making free use of an infrastructure which is mostly installed, maintained and used for/by the commercials. If they have no need anymore for it, then either we have to find a way to convince the authorities to keep them in place, or pay for them ourselves.