The reason the advantage of Single conductor transmission line be changed to non-singular conductor transmission line
For 2., the lower inductance means lower loss. 

There are two main sources of losses in high power transmission lines.  One is the I^2*R  (resistive) loss, and the other is the loss caused by the self inductance of the transmission line.  Hence reducing the inductance lowers the loss.

Note - eliminating the inductive losses is a big advantage of DC transmission systems.