I guess I'm not too familiar with the structure of Spanish colonies in the new world, so I don't know how close different areas were. I wouldn't expect 70% of South America and all of Central America to have coalesced into a single country, but the number of countries for that size seems odd to me.
Hey, this is a really good question! You should check out this section in the FAQ. If I may sum up many of these threads, some of the reasons that Spanish America broke apart into so many countries included significant geographic separation between population centers (which fostered unique political trajectories), vast diversity within and between localities and regions, a complete lack of political cohesion around Spanish institutions other than the monarchy itself, varied interests between both the elite and common stratas of society that pulled regions in various directions, and the spontaneity of independence itself which occurred before the development of national identities or institutions.