Is a small heavyweight a better heavyweight?

A couple of years ago, there was a movement for a superheavyweight division based on the argument that the new modern heavyweights who towered around 6 and a half feet tall and weighed 250 pounds or more would take over the division and the more traditional "Joe Frazier" heavyweight would be a thing of the past. However, that talk has cooled substantially. Why? Why haven't the huge men taken over? Chris Byrd, Roy Jones, James Toney, Vassili Jirov, and even more traditional fighters like Holyfield, Tyson, etc. are big names in the sport now and are small heavyweights in the ring. True the Klitchko brothers, McCline, and (before retirement) Lennox Lewis are all huge men, but on any given night any of those men can be cold cocked by an opponent. So why doesn't size matter? Just looking for thoughts and opinions.