The Academy can be right occasionally. Usually its by accident. Here are some other films that i think were the right choices (if you don't mind me going back a bit further):

Casablanca: It seems only like an obvious choice for Best Picture in hindsight, but at the time Hollywood though it would go to Son of Bernadette or For Whom the Bell Tolls, showier pictures

The Best Years of our Lives: William Wyler may be history most undervalued greatest director because he didn't have a style the way John Ford or Frank Capra. Best Years tells the story of what it is like for soldiers to come home after war in a way that no film had done before and few films have done as well since. It cries out to be released in a DVD or streaming film that does it justice

Marty: "What do you want to do tonight? I don't know. What do you want to do? Possibly the very first independent film to win Best Picture and there have been few films as simply brilliant before or since.

Million Dollar Baby: After Mystic River lost Best Picture and Director, I told my mother: "Clint'll win next year." I swear to God I was joking. Eastwood has directed better films before and since, but there are very few where he's given a better performance. It starts out as a slightly conventional fight film and then it takes a left turn into tragedy that is still profoundly moving twenty years later. This might have been a make up Oscar for Eastwood, but I still think it would have won on its own merits.