I've always thought it's a generational thing. We usually hold players from our youth in higher esteem than those in later life.
Maybe we're just more impressionable and look up to them with greater reverence or, perhaps simply, we employ rose-tinted glasses when remembering the past.
Certainly, I've always been in the camp that believes Diego Maradona to be the greatest footballer that ever lived - those older than me might nominate George Best or Pele. The current generation would argue the case of Lionel Messi or Cristiano Ronaldo, and it's hard to refute the statistics that back this up.