In winter, I wear my Ron Hill running tights, long sleeve technical top and a beanie hat to keep the head warm. Oh and gloves too. I don`t go out in the winter wearing shorts unless racing.
I hate the cold and sometimes it best to have your body protected and insulated. When out running, your body warms up like central heating. Running outside wearing shorts is OK during spring and summer. But in the winter, for me, no. Unless you love the cold.