Why isnt Lennox Lewis recognized as the greatest heavyweight of all time?

He beat Tyson (when he was older than Tyson), Holyfield, Morrison, Bruno and a bunch of others who were no slackers. 41-2-1. Do people really think Joe Louis or Rocky Marciano couldve taken him down? We all love Ali but he had his losses. He makes the top 10 lists but is never called The Greatest. My guess is that its bc he's not as exciting to watch- but he fights w calculated power and intelligence.