Beagle
The highly desirable utopia you describe will never happen, not in Europe anyway.
As I've suggested, you can get close enough though.
Navbox and Flitestar will both load up a non-IFR GPS. Navbox requires the use of printed charts. Flitestar can have the Jepp VFR/GPS charts in it.
IMV, for VFR or IFR flight at nonpressurised levels, one needs a lot more than just a list of TAFs and METARs along the planned route and the F215. One looks at other sources e.g. SigWX, various bits of GFS. So this looks very difficult to do automatically, to everyone's liking.
Again for VFR flight, Notams are a must and in principle one could set up an interface into the AIS database and stuff the planned route into the Narrow Route Briefing. I believe that Navbox has done a tie-up with Avbrief which is supposed to do just this, but last time I tried it (some months ago) I could not get it to work. However, entering the route into the NRB form is trivial enough.
You don't need to fly daily to remain familiar with a modern GPS, for basic en route operations. And terminal operations are not go get a lot of exercise in the UK right now...
A&C
I think airliners never had much of a problem (well other than going into the odd bit of the Andes because their dead reckoning went wrong) because they have been under radar control for many years, they don't have to avoid CAS, icing is rarely a problem (equipment plus mach heating), and they have 2 pilots. I have better nav gear than Concorde had when it retired (I went into the cockpit after landing). A lot of the technology drive for GA appears to be flash marketing (big LCDs especially) but it should make single pilot IFR safer, through a reduction in cockpit workload.