The fourth criterion might go some way to explaining why the list it so heavyweight oriented, but its still a horrible list, even factoring that into it.
Obviously Dempsey and Johnson come under the "Mainstream appeal" factors heavily. Same with Ali and Louis. This certainly explains the amount of heavies in the top 10.
I don't like these criteria. 1st - Who they fought, then who they beat and then who they did well against; all taking into consideration factors like age, peak, venue, weight class etc... I don't consider spectacular KO's any more significant than points wins. 2nd - What could they do, skills, talent, psychology, etc... 3rd - How long they did it for... 4th - historical significance