Say again s l o w l y
Back after a while, just read your post about the DA40 avionics.
I'd say a 2 day course should be mandatory not only for the more integrated "glass cockpits" but for anything as complex as a GNS430/530/KLN94 etc.
The glass cockpit just integrates the stuff into one display unit.
I suppose that nothing happens because people learn it as they go along. That's what I did, but it wasted a lot of time.
I did a Honeywell GPS training course once but very little of it rubbed off, because the instructor just worked through the features, rather than how to use them for real IFR flight. And some of it one isn't ever likely to use, e.g. the specific features for automated sequencing along a GPS approach, or flying back course localisers.
These debates will run and run, because GPS can never be included in the 45hr PPL.