I also remember some original Star Wars actors despised the movies, doing them only for money, and then were surprised by the popularity and disgusted by the fact those movies represented their "life's work" they were best known for.
Proof - older gens consider them eternal classics, most of the young these days couldn't care less. Give them some true classics like Spartacus or Orson Welles and they are more intrigued.
All that bashing said, I love them all, even the crappiest prequels, but then again I love tons of sci-fi and fantasy.
I don't think your proof works as well as you expect. Counterpoint: pick a random person, tell them to watch Citizen Kane, and tell them that it's "the greatest film ever made". I think they will have... opinions about that title. On a quick search, "A new hope" has higher audience ratings that "Citizen Kane" in IMDB, Rotten Tomatoes, and Metacritic.
The original trilogy is not perfect, but it definitely is a true classic under any definition of the term.