How much energy does it take for the PC to be on and the user to type out that email manually?

I assume we will get to a point where energy required starts to reduce as the computing power increases with moores law. However, it's awful for the environment in the mean time.

I don't doub that rather than reducing energy, instead they will use more complex models requiring more power for these tasks for the foreseeable future. However eventually it will be diminishing returns on power and efficiency will be more profitable.