Hmm, so birds have an AI research department now? Title could be fixed by adding "anatomy", so "bird anatomy makes better bipedal bots".
Anyway, it seems reverse knee legs aren't great for upright bipedal walking, especially if you want hands to do something else. Bipedal animals with reverse knees have either wings or very small hands (kangaroo), and I would guess it's because the center of gravity with reverse knees has to be relatively low. Humans evolved to walk upright for purposes of using hands at the same time.
Penguins are another unique animal, they have very low ankles (and high knees, hence the waddling) and also seem to use their hands more than other birds.
And kangaroos? Okay, so their knees are possibly somewhat more inconspicuous, but looking at a kangaroo skeleton, what to my eyes looks like their ankles also actually is their ankles.
Whereas with birds the confusion comes in because
a) they're walking on their toes, so what to us looks like an ankle is in fact a toe joint, and then moving further up what we think looks like a "reverse knee" is in fact the actual ankle, and
b) their true knees are usually hidden somewhere beneath their feathers
Anyway, it seems reverse knee legs aren't great for upright bipedal walking, especially if you want hands to do something else. Bipedal animals with reverse knees have either wings or very small hands (kangaroo), and I would guess it's because the center of gravity with reverse knees has to be relatively low. Humans evolved to walk upright for purposes of using hands at the same time.