Maybe I'm just not used to this visualization, but I didn't find it particularly easy to see the thing it was intended to show: which countries are over- or under-represented in Wikipedia coverage, relative to their size. It seems like this could have been conveyed just as well by a table listing the population and size, sorted by some normalized ratio of those. I don't see how knowing the geographical position, shape, and absolute size of the countries, as conveyed by the map, actually helps demonstrate the point.