I’m thinking that you wouldn’t be able to have superconducting wires with AC electricity, as the switching (the direction of flow of electrons moving backwards and forwards) that occurs in AC current would break Cooper pairs. Also, this paper here also seems to suggest that even in superconductors, there still exists a (surface) resistance.
If we could use superconductors in DC power lines, the lack of resistance would mean we can transmit electricity without loss to heat, which would allow for very large current densities - even in thin wires - with zero energy loss. This would reduce demand for the building of more power stations and even reduce the current costs of power. So it seems exceedingly economically viable. The potential benefits of renewable energy devices/environmentally friendly energy in conjunction with this could not be understated.
However maintaining the low critical temperature needed in the wires would be extremely difficult. At the least it would probably be more expensive, labour and energy intensive to do this, that any benefit would be significantly outweighed by this burden.
But if we could find methods to circumvent these problems, the payoff to humanity would be immeasurable.