I don't want to start a "Bitcoin is useless" flameware but to your question: the reason why the energy consumption of proof-of-work is important is because soci

I don't want to start a "Bitcoin is useless" flameware but to your question: the reason why the energy consumption of proof-of-work is important is because society hasn't found a purpose for Bitcoin to exist yet. Therefore, the energy consumed is considered "wasted" whereas it could have been used for something society already deems useful, like keeping the lights on.