It is good engineering practice to seek energy efficiency. It's not just good, it's expected, it's not optional any more. It's hard to believe that an open-ended energy requirement was anticipated in the design of bitcoin. There may have been some rationale about increasing powerful and efficient computing meeting needs in the future, but that doesn't count for much. If I had a bitcoin for every "it's gonna be great!" thing that was just around the corner and then never came to pass, I would have quite a pile of game tokens, I could use them to buy one of them there jet packs everyone uses to commute these days 

Since the bitcoin system was orphaned by its designer and there doesn't seem to be anyone else up to taking architectural ownership, there's no reason to believe that the core of it will evolve. Consequently, the best case expectation is that progress will replace bitcoin with something that addresses its shortcomings, both technical  ( for one, it's an energy pig ) and behavioral ( de facto centralization of its operations in currency exchanges and other institutions cloned from the bad world some would tell you that bitcoin will replace ).

Other than that,  I agree with you, raping children is not nearly as bad as raping and killing them, which is why a comparative advantage case is often hard to win