Efficiency is still a net good. Even if you don't believe that CO2 in the atmosphere causes climate change, every form of electricity generation has negative side effects for society, including renewables.
Normally the benefits greatly outweigh the costs, but that's not true for proof-of-work systems when considered in light of the alternatives.
>Bitcoin could definitely be more energy efficient
Exactly. One way to do that would be to use something other than proof of work.
>Why are we attacking Bitcoin for using electricity instead of simply pushing for more renewable energy sources?
Because increasing the demand for electricity more than necessary increases the cost to all of us––both the direct economic cost in our electricity bills and the environmental and societal costs. This is true whether the energy is renewable or not.
>At the end of the day it seems to me that any free society that supplies energy as a service shouldn’t be dictating what individuals do with that electricity as long as they pay for it
Wasteful energy use causes problems that society as a whole has to bear. Think about what would happen if we said things like "any free society that permits land ownership should permit nuclear waste disposal on any private property." It just doesn't work out, because society as a whole ends up paying the cost.