Few ever consider the great possible future of LED headlights. The nice thing about LEDs is that they are ever improving and the headlight can be optically engineered to produce the common beam pattern that we are so used to. Brighter and brighter LEDs are being produced. Single die LEDs can produce 200 lumens of light and multiple die LEDs can produce up to 1000 lumens now (Osram's new LED). I bet by the end of this decade, they will get something right with a form of LED headlights. I wouldn't be so negative yet. It is a new technology that is improving. It will have problems early on.
I am working (ever so slowly) on LED headlights for a friend. I am so busy with classwork that I haven't finished, but from what I seen so far, LEDs can be used solely for lighting at night. I am looking forward to my next project where I will make another set of headlights for another friend. It will use today's technology and use less LED emitters, as well as better optics. I know it is not DOT certified (I heard all of that, lets not bring that up here), but it is competitive with the brightness with most headlights today.
As for places with poor weather, they can always implement already used technologies to melt ice and snow. I live in Ohio so I understand that happens. They can use the same type of heating elements that are used in side mirrors or rear windows to take care of snow and ice. As for taillights, I do not see why they do not use incandescents for normal parking lights (on all the time), then use LEDs for the brighter and more instant brake lights. A combo of LEDs and light bulbs can be used for both modes of taillights, too.
What is worse, when a select few have a little snow blocking their taillights to block the light during winter months, or when what seems like 20% of everyone driving has a burned out taillight(s) all year round? Going to school in Cincinnati (like most cities), you will find so many cars with burned out headlights and taillights that it bothers me (and in some cases, frightens me). If they are not burned out, then they are installed improperly or are aging and grow dim. I always hate the white taillights when the red lens is broken and white light exits the back.
I really do not want to argue with someone with so much experience in the field, but if automakers do it right, LEDs can make some great headlights and taillights. They can engineer headlights correctly and use warmer colored white LEDs and they can avoid glare that occurs with some HID headlights.
-Tony