People have already made some good points on here... But I think that it simply comes down to he fact that past fighter's have already had their legacy's set.. Think about it... Currently the fans will always want the top fighters to face someone else, it's just the way it is... But when remembering fighters of old, there's generally none of that, " oh, he didn't fight so and so, and he didn't do this"... Likely because most people generally don't even know who those so and so's are... I know I probably wouldn't when discussing many past greats. Most of us weren't around to know who was being sold to the fans as the next best thing at that time. When your talking about people fighting today there's always someone else who could potentially beat them, and with enough hype around them to warrant the fight.... That doesn't mean people will remember them that way in years to come.