Ramanuja, a famous Vaishnava acharya of South India is considered as an avatara (incarnation) by most of his followers.
During his life, it is said that he traveled to many places for establishing the pancharatra mode of worship in the temples.
For example, I am quoting the following passages from Nitaaiveda (authentic gaudiya vaishnava site) and KamakotimandAli (another famous site for Vedanta)
RAmAnuja’s work in the Puri Temple has been described by AnantAchArya in PrapannAmrita. [excerpt from History of Medieval Vaishnavism in Orissa]
RAmAnuja had the divine service performed by other BrAhmins, according to the PAncharAtra rite, which was observed in the ShrIrangam temple. Consternation and disgrace stared at the face of the priests and at nightfall they assembled before the altar of JagannAth. “Hark thee, O Lord” they cried. “RAmAnuja seeketh to introduce changes in the form of Thy worship. We belong to the old school and we abhor such changes. Save us, we beseech Thee, from this imperious Sannyasi. Otherwise we will die before Thee.”
Ramanujacarya visited Puri in the twelfth century. Ramanujacarya is the propagator of the Sri sampradaya. He was a great Vaisnava acarya and also famous as very learned personality. He preached the doctrine of visista advaitavad and vigorously opposed the teachings of Sankarcharya At that time King Choda Ganga Deva ruled the state of Orissa. Ramanuja had much influence over the king. Ramanuja recognized Lord Jagannath as Maha-Vishnu. He saw that the Lord was being worshiped with the mixture of different processes. He was concerned that low-caste people, such as Daitapatis could take part in offering puja. Ramanuja argued that Lord Jagannath should be worshiped with the Vedic process only. He wanted to change the process of puja in Jagannath temple. He presented many changes to the king and made him agree to his proposals. Jagannaths sevaks objected to the new system. But the King would not listen to their appeals. Finally the date was fixed for Ramanuja to change the puja process in Jagannath temple. The King and all of the brahmanas arrived at the temple in the early morning. They announced that from that day, a new system of worship would be introduced by the great acarya, Ramanuja. Everyone, including the king, waited anxiously at the temple for the arrival of Ramanujacarya. But he never showed. After waiting for a long time, the king ordered the pujari to start the worship of Lord Jagannath according to the previous system.
Then the king ordered his minister to find Ramanujacarya. It was discovered that during the previous night while Ramanujacharya was sleeping, Lord Jagannath appeared to him. The Lord chastised him, "Who are you to change my puja system? Let My devotees worship me as they have been worshiping Me from the beginning. They are my special devotees. I have a special relationship with them. You do not understand this. Do not disturb them. Get out of here!"
The Lord flew Ramanuja out of Orissa by the help of Garuda. The next day Ra¬manuja was found in South India in a village called Kurma Kshetra. (Sri Kurmam/ Andhra Pradesh).
Note: RAmAnuja is known to have never returned to Puri again.
Another incident where he changed the temple worship in many VaikhAnasa temples.
Inscriptions from perhaps the eighth century CE identify Vaikhanasas as temple priests, and from the end of the tenth century they are prominently mentioned in South Indian inscriptions. Vaikhanasas were the priests of Vaishnava temples. They were not merely ritual priests, but were trusted with administering the temples and their lands. With the rise of the Shri Vaishnavas the Vaikhanasas declined in their temple role. Ramanuja, leader of the Shri Vaishnavas and the first organiser of temple administration at Srirangam Temple, replaced the Vaikhanasa system of worship with the more liberal Pancaratra system, expanded the fivefold division of temple servants into tenfold, and gave an important part in ritual to sudra, lowest caste, ascetics. This change spread to other Vaishnava temples.
Based on such incidents, my questions are:
What was the need to change the ancient temple worship forms?
What was the need to insist those were were not willing to change?
Most important questions:
If rAmAnuja was an incarnation of the lord then how come he had such an ordeal with Lord Jagannatha himself?
Why would Lord Jagannatha deport one of his avataras to Srikurmam?
"If indeed he was an avatara then how come not successful in this mission?"