The thing is, every system costs money. Sure it would be cool to have many options, solar, wind and even a water turbine if you have a creek. But who can afford all that?
The power-heat coupling system was also not cheap, but still reasonable in price. 10 grand or so, some years ago. That was without the heating radiators in the house, which usually already exist from the previous heating system. And yes, surplus electricity could be used for heating, thats fairly cheap to do.