It is Lord Krishna’s years in Brindavan that are celebrated more in the verses of the Azhvars than His later years. And the Krishna avatara is sung of in more verses than the Rama avatara, explained M.A. Venkatakrishnan in a discourse. Periyazhvar sang three times to ward off evil eyes from Krishna, but Rama has just one such verse dedicated to Him. The reason for this is the difference in the childhood years of Rama and Krishna.
Rama was heir to the kingdom. His birth was celebrated by the entire kingdom. Krishna was born in a jail and His life was in danger from the moment of His birth. In fact, there existed a threat to His life even before He was born. There was no time for Vasudeva and Devaki to rejoice in His birth, for they had to take the child to safety. Should any danger even remotely threaten Rama, He had Dasaratha to protect Him, for Dasaratha was a brave king who could drive a chariot in all directions and who had once saved Indra. So Rama was safe and secure.
As for Krishna, His foster father Nandagopa is described by Parasara Bhattar as a mild-mannered man who would tread softly so as not to hurt even the grass on the ground. Krishna did not live in a secure environment. Rama was surrounded by wise men who would ensure His welfare. The citizens of Ayodhya too would protect Rama. Krishna had no wise men to guide Him. The residents of Brindavan adored Krishna, but they were unlettered, innocent people. Also, while Rama was obedient, Krishna was naughty. For all these reasons, Periyazhvar offered more verses for Krishna’s protection than for Rama’s.
Krishna’s life may be compared to sugarcane. Krishna’s life before He went to Brindavan may be compared to the bottom part of the sugarcane which is covered in mud. Krishna’s life, likewise, began in a dark, dank jail. The later years of His life may be compared to the tip of the sugarcane, which is never consumed. The later years do not have the charm of Krishna’s life in Brindavan. But Krishna’s years in Brindavan are delightful, like the sweet middle portion of the sugarcane. That is why His years in Brindavan are sung of more than His later years.