Because there is an abundance of inverter generators with dead inverters that can be had cheap or free, and its either not possible or prohibitively expensive to obtain a replacement inverter board.
Small high current low voltage DC generators suitable for direct charging of battery banks are neither common place nor cheap. At least not right now, in the west.
So potentially it would provide a cheap high current DC power supply, that you can't easily buy off the shelf.
And if rewinding the stator was too hard, another possible option would to be to buy another stator (and rotor, if need be) wound for your desired voltage straight of china, but you would want to take care to make sure it will fit on the engine of whatever inverter generator you wound up with.
Seriously though, converting a V8 to a 3 cylinder is orders of magnitude more complicated and less practical than rewinding a few poles on a stator. I can't of any reason why anyone would do that, unless you lived in some bizarre alternate universe with an over abundance of V8 engines and absolutely no access to any smaller engines, and you absolutely had to have a smaller engine.
Its not unheard of for guys to rewind motorcycle stators (I've done it myself), and they look very similar to the stator in an inverter generator. I just don't see why it would be such a big deal.
