You would increase the cost/complexity of every appliance.

It’s easier to just have the solar inverter and battery system independent of the equipment. It’s relatively inexpensive to retrofit a home for an auxiliary power source. The complexity is when you tie into the grid.

Some appliances are solar ready. Some hvac systems and pool systems accept direct solar panel connections.

If i weee i charge, i would require all homes to be able to support solar panels and a battery system. The cost to do so at time of construction is insignificant.