Does it NEED to? perhaps I need a special robot to clean my stairs, if there is any clutter on it, it just dumps it at the top/bottom. Then a different robot puts the clutter away. My robot vacuum/mop does a great job with floors already, so I don't need the clutter robot to handle floor cleaning. I likewise need a robot to fold my laundry, but maybe it turns the folded laundry over to the clutter robot to put away or something?

The point is I don't need a general purpose robot of any form. I have various specific tasks I need done, I don't care how many robots are involved. I do care that the total is affordable. I do care that the total doesn't take up "too much" space. I do care that the job is done well. I don't want to think about any of it unless I want to think about it (sometimes it is fun to watch my robot vacuum work. Sometimes I want a specific mess cleaned up first and then go away before guests arrive). Maybe a general purpose robot is the best answer, maybe not - since I'm not [currently] designing such robots I expect those who are experts to figure out the best form - which is probably a compromise.

So you can buy one robot that does everything and stays busy all day, or a bunch of robots that each do one thing and otherwise stay in closets.

If you have a factory, idle equipment costs you money. Right now our factories have only specialized robots, but they still have lots of people because it's too expensive to do the remaining tasks with specialized robots. We need general-purpose workers for the tasks we're not doing 24 hours every day.

This makes general-purpose robots look like the cheapest option for many tasks, but that could be offset if they cost a lot more. But the more of anything we build, the cheaper the thing ends up being. A very large number of identical robots will probably end up costing less than smaller numbers of lots of special purpose robots.

> If you have a factory, idle equipment costs you money

True, but that isn't the whole story. Where I live most factories have their own snow removal equipment even though it is only used a few days per year and sits idle the rest of the time. While it costs money to have it sit idle, it costs even more to have the whole factory idle until the snow melts. (or the people you hire get around to your factory).

> Right now our factories have only specialized robots, but they still have lots of people because it's too expensive to do the remaining tasks with specialized robots.

And when they decide people are too expensive they replace them not with general purpose robots but more special purpose robots.

> A very large number of identical robots will probably end up costing less than smaller numbers of lots of special purpose robots.

Maybe. It isn't clear. A general purpose robot could be more expensive - I only need one while I "need" one vacuum robot per floor meaning that special purpose robot scales better. And that vacuum robot is also a lot simpler meaning it will be cheaper to own 2 than to have 1 general purpose robot.

The question then is the general purpose robot cheaper because you only have 1 instead of an army of special purpose robots. We do not know (today).

So the point is just to allow them to use existing tools ? Essentially self imposing our own limits on them, I don't really see how that makes sense.

Just look at the animal kingdom, there are a bunch of stuff that would be extremely useful, tails, extra limbs, extra joints, no separated head, longer limbs &c.

The animal kingdom also lacked built infrastructure and tools. If the environment had been full of hand tools for a hundred million years, how many animals would have evolved to use them?

Some of your listed features could still work though. A humanoid robot doesn't have to have exactly the same form as humans, as long as it's close enough to use our stuff, ride around in our vehicles, etc. The alternative is to build all new infrastructure and tools that don't work for humans; I'm not sure why we would want that.