It is a big strokefest movie. It involves 1960's theme's and movements that Hollywood and the Hippie generation loves. Add the music that generation loves and you get Forrest Gump.
Look at commercials and clothes today. It is all 1980's styles because people of Generation X are in control. This can be applied to Forrest Gump. It has all the themes for people in 1994. Vietnam, Watergate, Protest...etc... Add in a "Being There" feel and you got the formula. I like all the actors in the movie but I dislike the forced agenda in the movie.