ok me saying "in opposing current a voltage is developed" isnt really true
it is a way of looking at a situation that is only valid if viewed that way. IF you use that arguement outside the region it was formed it, it is broken.
Current flows because the existance of voltage, not the other way round.
You can never had current without voltage. BUT you can have voltage without current (doesn't mean you can measure it)
IF you left the coils of the winding open then a voltage would be developed. now if you were to just use that voltage as the input to an OPAMP (OPAMP with extreamly high input impedance) then you would get negliable current flowing.
However, the guitar would not soud good, it needs some current to flow to get the magentic core to a flux density so it sounds correct. Thus some form of load to allow current to flow is added