Because all your DC appliances use low voltage. Low voltage requires thick cables at long distances: For example, look at how thick auto battery cables are. Wiring a house with cables that thick is absurdly expensive.
In theory, we could use high voltage DC, but then each appliance will still need something to drop the voltage.
I personally like how USB is becoming the low voltage standard. You can find outlets with USB built in.
48VDC at 20A is more than enough for most loads in a home (960W) and 12 gauge wire (standard in many homes) will handle that just fine. Auto battery cables are thick because they have to supply hundreds of amps at 12V. Different situation.
Out of about 100 things that plug in to the wall in an average home you've just listed 5 that won't work. (You missed the water heater and the clothes dryer BTW). This is exactly what I meant by "most."
There's no reason homes couldn't distribute 120Vdc over the same wire guage used for ac since all applience motors are now dc and all electronic PSUs are switched mode. Each appliance already has "something to drop the voltage".
Just go to a higher voltage already, if you go for DC. Most computers e.g. are fine with 300~350 V DC (and would not be fine with 120 V DC, as the high-voltage side of their power supplies isn't designed for the current you'd have at "just" 120 V).
The US uses 120v AC because incandescent light bulbs and heaters that ran at 100v DC would work at 120v AC. It allowed upgrading the original DC grids to AC with minimal impact.
In theory, we could use high voltage DC, but then each appliance will still need something to drop the voltage.
I personally like how USB is becoming the low voltage standard. You can find outlets with USB built in.