as a person who has spent a fair amount of time researching the current state of the art for battery technology, both in watt-hours per kilogram and watt-hours per cubic cm: I have to agree with you. Anything with sufficient processing power to drive a high resolution, 60 fps AR display is going to need a good amount of battery. And that amount of battery is not going to fit into a google glass or hololens sized thing without needing to be recharged every half hour of usage.