Re: exactly the sort of thing we want machines to do.
There are two components to profit, cost and revenue.
If the robots can do a lot more work, you can (potentially, at least) collect more revenue by managing more of the inventory yourself and/or selling more own-label products versus third party products. Your profit increases if your revenue increases by more than your cost increased from deprecating the capital expense of the robots (or more likely in 2021, leasing them) and converting warehouse staffers into higher paid robot repairers.
Down the road when they can offer robots capable of robot repair, they can fire all the humans!