Yeah, but.... the US govt mint folks have their collective heads up their collective butts if they think they can get people to accept a dollar coin. Just ain't gonna happen. People just don't like carrying around a pocketfull of worthless change, especially coins that no vending machine takes, especially since most vending machines take bills. Paper money is convenient. We seem to have grown beyond the silly notion that metal money has some kind of 'intrinsic' value.

A dollar is not worthless; it is "really" worth between five and ten cents, depending on your base year and index of price level change.

Note that in European countries large denomination coins work just fine. Coins do not have to be large. For example, the old five dollar gold piece was smaller than a penny (which created problems, because in San Francisco it was the exact same size as a bus token, and by mistake people would put them (now worth more than a hundred dollars)into the fare machine. The twenty dollar gold piece was roughly the same size as a half dollar.

Let the dime be the new lowest denomination coin, then a small fifty cent piece (about the same size as a nickel, maybe with a milled edge), and then also a small (thirteen sided?) dollar coin. The five and ten dollar coins would be larger and worth what fifty cent pieces and silver dollars used to be. I hate carrying around wads of one dollar bills.