Your clonning a thread, this has been discussed a lot but no worries. To awnser your question though
1-Protection: Outside Konoha the 4th was not well liked. Epecially by the Hidden Rock Village. They didn't want to paint a target on his back.
2-They didn't want him to get special treatment or favors being the 4th's son. They wanted him to grow up not being spoiled.
3- To protect the Namikaze name: The 4th sealing the Kyuubi in his own could seem like a selfish attempt to put power in his family
Hope that awnsers your question.
