In reality, I think that heater elements will actually exacerbate the problem. I'll explain:

I have never heard of any manufacturer (or aftermarket product) relying on defroster wires on or embedded into the front lens of the headlight to clear off snow and ice. In all cases where such a clearing strategy is employed, it uses a spray of windshield defrosting fluid (i.e., the same solution used to clean windshields), sometimes with the additional use of heater element either in the nozzle itself, or (in certain M-B models), a heater in the washer fluid container.

I find, here in the northeast, that when I'm driving in snowy weather, the heat of the headlights themselves is more than enough to melt snow and ice off the front; however, their brightness is often reduced not by a layer of snow or ice but by the spray of salty water (from the road deicing), leaving the salt to cake up on the headlight lenses. Further heating from your idea of heater wires will only exacerbate the problem by more quickly precipitating the salt out of the salty slush thrown on the headlights. Instead, you need to flush it away by dissolving the salt in a fluid wash.