I personally prefer the big, bruising power backs, but in all fairness, the above strikes me as an overstatement. Obviously, three 200lb smurfs who've succeeded in the league and who've won are Walter Payton, Tony Dorsett and Marcus Allen. And if we are to consider Campbell a winner, then the smurf Thurman Thomas needs to also be considered a winner and introduced into the list of winning RBs. But again, no way in hell would I take the helmetless one to Campbell if I'm building a team. This, however, is a personal, subjective preference toward a certain type of runner and a certain brand of football and I'm not so sure there really is an objective formula as to which style of runner or which brand of football is more conducive to winning in the NFL.
Now, Sayers was way before my time and I regret that I never got a chance to see him play. But I know many people who have lived through that era as football fans and invariably, Jim Brown and Gale Sayers are two names that come up time and time again when an argument on the greatest RB is instigated. This in turn tells me that Sayers, despite the short career and relatively weak career stats he put up, played the game in such a manner that he either changed the game to a certain extent or at the very least left an indelible, lasting impression on the fans. I can't imagine a RB today single-handedly scoring 36 points as did Sayers. And as important as total career stats are when reflecting on a certain player's career, I think it's nearly important to reflect on a certain player's impact on the game itself or a certain era in which he played. Thus, I've no problem with the mercurial Sayers having been enshrined. But you're right. I am somewhat biased because I've seen Brian's Song.
Lastly, I hope you get around to posting, if you've not done so already, why Lee Roy Selmon or Howie Long are in the Hall over Andre Tippett.