A more apt comparison might be coal fired steam. It was very unwieldy but replaced horses in some ways. Railroads and steam ships changed the world but still th

A more apt comparison might be coal fired steam. It was very unwieldy but replaced horses in some ways. Railroads and steam ships changed the world but still the technology was too heavy for personal mobility. If you can invent any kind of technology at will, sure, it can be great. Then let's have light and reliable space nuclear power plants. At the moment we are very far from that. It might have looked like a good choice forty years ago, but solar cells have improved a lot, as well as batteries. We do have some newish things on the nuclear side that could help, like gas cooled reactors or supercritical power cycles. You need to get the temperature up (to make the radiators small) and the power density too.