Network effects. The “we” you’re referring to could only be like 100 million at most, the vast majority of people don’t have the technical know-how to switch, or to articulate exactly why they feel miserable every time they log in for their daily fix.
I think it’s moreso a matter of evolution. We know humanoid bodies can do anything we can do, so we start with that and make incremental improvements from there. We already do have plenty of other body shapes for robots (6-axis arms, SPOT, drones, etc) but none of them are general-purpose. Also, the robot shown in the article is pretty clearly not fully humanoid, it has weird insect legs probably because it’s easier to control and it doubles as a vertical lift.