I agree that it would be niche today, but for devices that don't switch location in a house, one time wiring for DC "straight from the panels" so to speak makes sense for those devices that can draw a lot of power: it decreases the energy storage requirement on the inverter
Redesigning them so that in addition to AC, the devices have terminals for DC would probably not add that much to the cost. And off-grid may be niche, but partially because it's inconvenient to connect some of the larger loads that may require AC to your solar panels: if your going to buy energy buffering AC inverters for the house anyway, and don't understand or want to think about the price gradient for the energy buffer, people will obviously choose the setup you describe.
Redesigning them so that in addition to AC, the devices have terminals for DC would probably not add that much to the cost. And off-grid may be niche, but partially because it's inconvenient to connect some of the larger loads that may require AC to your solar panels: if your going to buy energy buffering AC inverters for the house anyway, and don't understand or want to think about the price gradient for the energy buffer, people will obviously choose the setup you describe.