You want robots that can do tasks humans can do but robot arms can't - which has a way of driving the design decisions. The more you move towards "flexible, mobile, multipurpose", the more you move towards the humanoid frames.

Just look up how vehicle interior assembly is performed now. Look at all the things that are still done by humans - all the different assembly stations, all the loading and unloading, all the installation operations, all the panels and wiring harnesses and plugs and bolts.

Then try to come up with a robot frame that would do all of it - every single operation that's currently done by a human - while being significantly less complex than a humanoid frame.

The design space constraints would choke the life out of you.