It seems you've written c² in units of Wh/kg? But the fact that per arbitrary mass, you can theoretically get more energetic reactions than by fission or even f

It seems you've written c² in units of Wh/kg? But the fact that per arbitrary mass, you can theoretically get more energetic reactions than by fission or even fusion doesn't mean comparing the productivity of fission to oil is silly. The issue is realistic ways of efficiently liberating and harnessing energy from matter. One better than fusion not impossible option is carefully feeding small black holes and extracting their huge output of energy. The feedstock for the black hole might even be lifted from the sun. In the meantime, fission is a productive and practical option to add to the energy mix that will more than serve until we've worked out fusion. One place I think I agree with you is that phrasing it as energy density, rather than focusing on efficiency of a given unit of mass or fuel at yielding energy can be a bit obscuring. That is, it's better to focus on sustainability of fuel source. Energy density (J/m^3 and J/kg, specific energy) are units more appropriate for talking about energy storage and bombs.