That works for a phone or a laptop when the manufacturer expects you to upgrade every few years. An average house might have dozens of different items, each with its own battery with different size, capacity and discharge needs. Its already hard to track down replacement batteries for older model phones and laptops, and its going to be ten times worse trying to find just the right battery for your specific model of printer or coffee machine years after its left production. Are appliances just supposed to be disposable now, or is it just a gimmick for the first couple of years you own something? In either case, it doesnt seem like the savings to the power grid could possibly justify the expense or the waste.