Lower Voltage
120 volts is already to low, going lower would present more cons than pros. People forget that because we're clinging to an obsolete voltage we've got millions of transformers wasting energy throughout buildings and millions more on utility poles spending most of their time at less than 5% load.
416Y/240 would consolidate 600Y/347, 480Y/277, 208Y/120, 240Δ/120 and split phase 240/120 into a single system. 416 volts for heat strips, 3 phase motors, commercial cooking equipment, high bay lighting and roadway fixtures with 240 volts for all other equipment and homes.
Since doubling the voltage for the same current means you can go twice the distance for the same % voltage drop or 4 times the distance at double the voltage with half the current for the same % voltage drop not even factoring the advantage of 3 phase over split phase; a single pole mount or pad mounted transformer can serve many more customers while being in the desired voltage drop bandwidth. Serving more customers means greater loading diversity with a utility transformer being subjected to a relatively flat load curve vs one with sharp peaks and troughs as in the modern US distribution system. For example, as people wake up homes begin pulling more power that begins to sharply drop as people leave for work, as people arrive for work load picks up in offices. As people head out for lunch load drops somewhat in factories and offices as load picks up in restaurants serving the lunch rush hour. Load drops at these places and pickups at work. As people leave work, load drops off at work but increases at homes as people make dinner, turn up the heat, ect. Defrost of food market refrigerators and freezers can take place at night. The combined 24 hour load of a community resembles a valley. Transformers are most efficient when driven continuously at around 80% load. In stark contrast all the 10, 15, 25 and 50kva transformers serving homes that see about a few amps most hours of the day with 200-300% 90 minute overloads in the morning and evenings.
In Europe it is common for a single 3 phase transformer to serve an entire village or at least large chunks of it- many homes, restaurants, businesses, schools, institutions, government, pump houses, ect making for a very efficient distribution system.
Lower voltages waste energy, take obscene amounts of resources, create unnecessary complexity, and are way less safe.