Your talking about an energy per hash ratio.  Yes, ASICs are a lot more efficient at producing hashes than a CPU.  But what is the end game of that?

When I meant more efficient I meant on a network wide scale making the amount of energy consumed per block going down. 

When CPUs were standard some electricity per block was used.  When GPUs became popular the network was consuming more electricity.  And when ASICs came into being the Bitcoin network devoured even more electricity per block than GPUs. 

Why have a network use a lot of energy per block with expensive hardware when you can have a network consume a little per block with cheap hardware?  Somewhere that extra money for extra maintenance for the more resource heavy network has to come from somewhere.  It is an operating cost.   To me the chain with the lower operational cost (all other things being equal) is better.  And that chain is the one that is more efficient.