Polarized power cords, fuses and some new wiring ( where required ) are installed in all of the radio sets I repair/restore. It makes sense from a safety perspective and also due to the fact that you never know what other component may fail in the future and I would rather replace a fuse and a bad component rather than have everything go up in smoke. Electrical standards were not well defined back in those days.
Some radios I leave non functional ( some smaller wooden battery sets for instance ) since they may not perform well or sound good…but they make nice display pieces. I also have some Atwater Kent models ( 30, 33, 36, 49 ) in various states of disrepair and I chose to get one working at any cost since the original resistors and inter-stage transformers were bad and some of the RF coils had to be rewound etc…in other words the changes I made were necessary since one cannot find original replacement parts due to the age of the radio ( almost 90 years at this point ).
The bottom line is that people like to listen to a good radio that is reliable, sounds good, performs well and is electrically safe. Some will end up being museum pieces for display or just sit on a shelf. There is a lot of history in some of these radios and being able to have one with first generation capacitor or resistor technology is interesting all in itself.