Yup! Lousy measure of lethality. I'm glad all the really big game animals I've killed with handguns don't know that my chosen firearms don't produce enough "energy" to really kill them - haha!
I don't hunt cape buffalo with a Daisy Red Ryder or even a .22 LR....someplace/somewhere foot-pounds of energy does play a role in the equation. Yes, it's not everything.....but it does have a place in the scheme of things.