Although Tobirama could choose the next Hokage himself, the appointment still needed the approval of the Daimyo and the Jonin to become official. Generally, the Daimyo would not reject the Hokage's recommendation, making that stage little more than a formality. The Jonin vote of confidence, however, left room for maneuvering.
When Konoha Ninja Village was first founded, it was an alliance of ninja clans gathered around the Senju Clan. Even clans as powerful as the Senju Clan and the Uchiha Clan could not completely disregard the opinions of their allies. Unless their survival and interests were at stake, powerful clans like the Hyuga and Sarutobi would not defy the Hokage's orders. If those interests were threatened, however, they would grow estranged from the Hokage and might even choose to leave Konoha Ninja Village.
The Hokage was a leader acknowledged by everyone in Konoha Ninja Village—or at least by most of them. If the Hokage could no longer represent the Konoha ninja, he would cease to be the village's leader. Thus, even someone as powerful as Hashirama had to take every ninja clan's views seriously and protect their interests. Otherwise, Konoha Ninja Village would soon splinter.
Hashirama's original ideal had been for the whole village to regard one another as family, but such tolerance did not exist among ninja clans whose strength and status differed so greatly. Recruiting civilian ninja had been intended to bridge the divide between clans and civilians, allowing both sides to gradually accept each other.
Yet this measure still met with covert resistance from the ninja clans. It was only after the Shinobi World War that it could be implemented on a large scale. This was not because the clans had suddenly grown a conscience, but because the enormous losses inflicted by the Shinobi World War forced