Autumn in Italy. Why should you go to Italy in September, October, November and December?

The golden and red vineyards and hills of Tuscany, Umbria or Marche, the warm water and empty beaches of Puglia, Calabria or Sardinia, few tourists and lower prices on the crowded Amalfi Coast and Cinque Terre seasons, rusty red leaves against still green meadows and white peaks of the Dolomites or maybe the huge amount of seasonal fruits, pleasant temperatures and the second spring in Sicily? Italy in September, October, November, early December. What are the pros and cons of travel in these months? What weather and what landscapes can you expect?