Lord Narayana came as Rama because He wanted to mingle freely with everyone, said V.S. Karunakarachariar in a discourse. But doesn’t Valmiki himself talk of Ravana samhara as the purpose of the avatara? Valmiki’s account was just a record of events. Suppose an official in Delhi wants to take a couple of days off to attend a wedding in Kancheepuram. His superiors refuse to give him leave. He then discovers that he has to meet some official in Kancheepuram. He uses this as an excuse to go to Kanchi. After attending the meeting in Kanchi, he also manages to attend the wedding. The official records in Delhi will say that he was in Kanchi on such and such a date, because of an official meeting. His being at the wedding is not going to be in the official records.
Likewise, Rama’s slaying of Ravana is the official record. The purpose of the avatara is not stated. Nammazhvar describes Rama as a pond in which asuras fell and died. A pond does not drag people and drown them. Likewise, the Lord did not have to come and fight Ravana. He happened to be here as Rama, and Ravana was killed because he abducted Sita. Had He not come as Rama, would He have been able to embrace Guha as a friend? He accepted the fruits that Sabari gave Him. His simplicity gladdened her heart. Would this have been possible, if He had resorted to remote killing of Ravana from His divine abode?