I don't think there's a single and simple answer. One thing that Cortez managed to do was "demystify" the mighty Aztecs in the eyes of the people conquered and supressed by the Aztecs.

There was unrest and violence in the region long before Cortez arrived on the scene, when he did he was the external catalyst to ignite the powder keg. When reading accounts of the conquest, information gathering, political scheming and negotiations were often more "decisive" than the actual fighting.