True, but they need more speed to give that much light (and if they're battery-powered, they need lots of battery to have a usable runtime). They can work with a standlight, but they'll drain the capacitor more quickly than an LED does.

LEDs are bright enough now that they can compete with halogen on brightness while retaining the efficiency advantages inherent to LED.

My go-to bike has a dynohub and LED lighting. My next commuter will also have a dynohub and LED lighting. I've got good battery lights for my other bikes (Superflash, Dinotte), but the convenience of generator lighting is just too nice to give up. I can't feel the drag from the wheel, either -- a breeze imparts more drag.

My setup, fyi: Shimano dynohub, B&M DLumotec Senso Plus headlight ("Senso" = automatically turns on in the dark; "Plus" = standlight), B&M Selectra 3-LED taillight with standlight circuit.