The usefulness seems questionable. LEDs have to be driven with current, so either you would have to have all LEDs in your house in series, with short-circuit switches for light switches, or you still have most of the electronics in every lamp/bulb anyway (saving only the rectifier and maybe needing only a smaller input filtering cap). The former is highly impractical (complete rewiring, one broken lamp makes all lamps in the house go dark, massive peak voltages if you have many lamps, ...), the latter isn't worth it either in device costs nor in efficiency gains (a shottky full-bridge rectifier probably eats less than half a percent of the lamp's power consumption at ~ 100 V supply voltage, less at higher voltages).