He smacked the best bowlers in the world around in World Series cricket when he was past his prime, and in the domestic cricket he played around the world. The 325 he scored in Australia was scored against an excellent attack that included Lillee, he played County Cricket, opening the batting alongside Gordon Greenidge at a time when all the Windies quicks were playing County Cricket. You're going about this on a purely stats based argument. Everyone that saw Barry Richards bat has talked about how brilliant he was. Bradman included him in his XI, Dicky Bird said he was one of the best players he's ever seen and talked about how Richards had such precise foot-movement, how he played the ball incredibly late and how he had so much time to do so. I understand why people don't regard Richards amongst the top few openers in the history of the game, because of the fact he only played 4 Tests, but anyone that's done any research about him knows what a fine player he was; and he was certainly on a completely different level to someone like Hayden AFAIC. I would have had no disputes had you picked Hobbs, Sutcliffe, Morris, Hutton or even Greenidge, as there's really not much between them, but I find it difficult to believe that Hayden's one of the 2 greatest opening batsmen of all-time.
I haven't picked Richards ahead of all of those players either, I've got him partnered by the legendary Jack Hobbs, a man I believe is the greatest opening batsman of all-time.