Well not everyone is developing a humanoid. There are other robots being worked upon.

But the answer to your question is robots, especially if they are mobile, have to operate in a world that was developed for humans. Thus having the human structure is vital. We are bipedal beings that constructed a world around it. This is how the general purpose bots can fit in.

As for the head, there is a reason: humans. Having a bunch of machines running around without heads and a camera like you say would freak people out. So for comfort, that is place there although there isnt really much need.

Maybe once they get past the WOW they will get on to more purpose built robots?

I think you will find they have a purpose very soon. My guess is we see use cases rolling out in the next 12-18 months.