Couldn't agree more. There should be no restriction on using an electronic calculator for PPL navigation training as far as I'm concerned. Although personally I find the circular slide rule useful for some applications.
Do any of the latest hand-held GPS systems include a flight planning calculator? Having entered route waypoints, it wouldn't be rocket science to enter planned IAS, ALT, W/V, OAT and fuel consumption to obtain GS, heading and leg time for each leg. Then send it to a printer for your paper back-up in case the system dumps in flight.
Ideally, of course, the W/V and OAT would be available on-line....