What's peculiar is, both examples have two glaring problems with them:
Voice coils sit around permanent magnets and pole pieces.
Motor and transformer windings sit around laminated iron.
If we had room temperature superconductors, it might be feasible to avoid the iron altogether:
Permanent magnets could be replaced by precharged superconductors. But they might not be as powerful (the critical field at room temperature, for a critical temperature not much higher than room temperature, will be fairly small).
Windings can be smaller and thinner, so we can put on more turns, compensating for the reduction in permeability. Windings can be interleaved, compensating for the increased leakage inductance (at some expense to isolation capacitance, though).
The incentive to these, in any case, is reducing the physical size, and reducing the losses, both conduction and core losses, so that the operating temperature can stay as close to room temperature as possible.
The interesting question becomes: even if RTS aren't capable of higher flux density than conventional methods, would they become worthwhile for most applications, and what would an optimal design look like?
Such an example might be the coreless motor,
https://en.wikipedia.org/wiki/Electric_motor#Ironless_or_coreless_rotor_motorwhich currently is optimized for acceleration only. An RTS version might be made with good enough specs that it's capable of delivering real power, at significant weight savings, if not volume savings (because volume is still necessary for the magnetic field density and curvature, even if for reasons very different from the conventional limitation of saturation).
If we had very high temperature superconductors,
everything would be absolutely blown out of the water, because we could get flux densities well over 1.5T without using cores, Halbach arrays or water cooling. But this seems somewhat unbelievable to me just yet.
Tim