Rain Man is not dated -- it has gotten better with age. It is not merely about autism -- Rain Man shows what it is like to deal with an intractable personality, or an intractable situation -- whether it's a terminal disease, alcoholism, or plain stubbornness.
One of Hoffman's best performances is in Straight Time, by the way, which isn't mentioned in the poll.
Hoffman deserves his two Oscars, and should have won a few more. His versatility is unmatched -- he followed The Graduate with Midnight Cowboy. Think of how difficult his role in Tootsie is -- he plays an out of work, egocentric actor who disguises himself as a woman, and while he learns internally what it is like to be a woman, he falls in love with Jessica Lange. There are so many layers of emotional complexity to this role, so many tides and currents of motivation, emotion and concealed desires, and Hoffman makes it all work, and makes it funny besides.
And then in Rain Man, Hoffman eschews the sound and fury of screwball comedy for the stillness and calm of an autistic man, a man whose scale of emotional expression is very narrow. Hoffman does more with less dialoge and less emotional expression than most actors could ever hope to pull off.
