1. It is not considered safe voltage, so you have all the downsides of the current AC grid with the downsides of high DC voltages
2. Nearly no equipment uses 120VDC by itself, so you would need specialized DC-DC converters that can deal with the 120VDC input to go down to usual voltages like 48VD, 24VDC or 12VDC
> Nearly no equipment uses 120VDC by itself, so you would need specialized DC-DC converters that can deal with the 120VDC input to go down to usual voltages like 48VD, 24VDC or 12VDC
Most switched-mode power supplies ought to cope with 120V DC. If you look at a circuit diagram the first thing they go through is a bridge rectifier and smoothing cap to provide a 165V (or 340V outside the US!) DC supply for the chopper.
I have some Thinkpad charging bricks I'm prepared to sacrifice for the cause, if you want me to try it.
DC also has issues with arcing, so switches get complicated and expensive.