Agreed, it's impractical. I walk 30 feet from my front door to my car, and maybe 50 yards from my car to work. Usually it's not raining. If I think it will (ie, weather report or incoming clouds) then of course I carry a rain jacket. But it's not all that often that we get rain.

If I totally misjudge the weather and get rained on, so what? I'm in an urban environment. It's easy enough to find a warm place or if need be, go buy some dry clothes or go home and change. I don't carry a backpack around with a change of clothes.