When comes to lower part it’s always bipedal (hard to balance) or wheels (low capabilities). Why no one makes 4-6 legs, insect like? That seems like an easier problem to solve while gives much better mobility.
I wonder how much of it is training data. We can very easily get training data of 'human tasks' because humans can wear tracking suits, and those suits track bipedal movement. Anything we train off that isn't bipedal (ie dogs) don't do human tasks, don't hold anything, so a different set of requirements.