Two years ago, Tesla's Optimus prototype was an underwhelming mess of exposed wires that could only operate in a carefully controlled stage presentation. Last night, Tesla's "We, Robot" event featured much more advanced Optimus prototypes that could walk around without tethers and interact directly with partygoers. It was an impressive demonstration of the advancement of a technology Tesla's Elon Musk said he thinks "will be the biggest product ever of any kind" (way to set reasonable expectations, there).