This "ranking" is just a gimmick, what practical use does it actually serve? It isn't like a Singapore citizen who wants to visit that 190th country can suddenly decide to become Japanese so they don't need to attend a consulate prior to their trip... (and that's assuming the 189 visa-free countries for Singaporeans and Japanese are aligned, which they probably aren't).
Also, destinations are not equal. Suppose tomorrow Abe says something that Trump takes as an insult and he decides to suspend Japan from the VWP, now Japan is on par with Singapore at 189, but it would be a stretch to claim they have "equal travel freedom" since a lot more people want to visit the US than certain other small countries. And how many people (apart from those who congregate on travel forums) actually want to visit 100+ countries?