Annanu and Enkidu were largely indifferent to war. They merely tried to understand it from the perspective of their own understanding.
Could war against outsiders benefit Uruk?
Perhaps it could, but at least in Annanu and Enkidu's understanding, the gains were not proportionate.
Although they had not been in contact with humans for long, and their position was somewhat strange due to the gods' deception—or perhaps because of the gods' own understanding—there was one fact they understood.
People died.
Humans had one life, and one life only.
After the Great Flood, when Enki and Mami created humanity for the second time, this was the "restriction" the gods had imposed upon mankind together.
Humans no longer possessed long, enduring lifespans. They could die of thirst in droughts, starve in famines, succumb to disease in plagues, grow old and die as time passed, or be killed by murder, hatred, or war.
Afterward, they would cast themselves into the underworld, never to return.
Because of these restraints, humans had become fragile. Yet because their lives were brief, they possessed the resolve to strive for better things. In contrast, Utnapishtim—the immortal survivor of the old humanity, lingering at the edge of the underworld—did nothing but curse everything forever.
Thus, such lives were precious to humans. And the labor force made up of those humans was even more precious to a king—to Gilgamesh.
There was still plenty of uncultivated wasteland around Uruk. If Gilgamesh had not been immersed in pleasure and lavishly using his army to invade other city-states, but had instead put that labor toward reclaiming land and expanding production, he could have gained far more than he ever could through war.
Of course, their thoughts might have been somewhat one-sided and idealistic, but—
They had strength, didn't they?
The reason Gilgamesh had looked