I think it's fantastic that washing machines would heat their own water...I'd be all over that if I ever find one. My hands are so leathered from work that I can stand unusually hot water temps directly on them. However, it's not about me, but about my 3yr old.
Demand WH's were all the rage but after installing dozens of them, including high-priced Bosch units, they have some issues. They have what is similar to a reed valve inside and if the demand heater is not used all the time, that valve will start to calcify. They have kits (wonder why) that replace the valve/seals, but there really is no practical way to ready a unit for vacation status.
I had one where I replaced the valve/seals after a long vacation and I never could restore the hot water fully to the unit. No Bosch tech could offer a solution either.
Needless to say, I'm not super high on those demand units (gas) and I think the electric ones are very energy inefficient. Takes a lot of amp draw to heat water with one of those electric demand units. And on any of them, a lot of water (wasted) has to pass through the fixture before you feel the hot water. Since it's a demand unit, there's no way to recirculate water to get instant hot water.
Kevin