Used to be a lot of us, back before LEDs got cheap. It used to be common to run MR16 halogen spots.

The problem I see with that is that until proven otherwise I'd bet those were extremely inefficient. The current limiting might be really crude in those which would lead to a lot of power being spent as heat. When you're designing to go onto a car, you can afford to just dump power as heat, nobody cares if it draws an extra 5 watts, but on a bicycle or flashlight it's a big deal.