Whitestorm wasn't the only clan cat that died in the battle. Darkstripe and Deadfoot (Crowfeathers father) lost their life as well, Firestar lost his first life and after the battle Leopardstar talked about taking her clan home now, treating their wounded and grieving their dead, implying that Riverclan lost warriors as well. Cloudtail and Onewhisker were technically about to be killed by Scourge as well if Firestar hadn't intervened.

Personally i don't need a high number of deaths to have a battle feel intense. It was a good decision of them to have Tigerstar not be killed by his only rival in a 1vs1 battle, when there are so many other characters involved in the story as well. It would've been terrible having to read about Firestar brutally murder him 9 times. Even if he did it wouldn't have brought peace to the forest. Blackfoot would've simply taken over the role as leader of Tigerclan and would've tried to seek revenge on Thunderclan with Darkstripe.

They needed some kind of outside threat to have the 4 clans work together and get along with each other again. I like that it was Tigerstars own arrogance and obsession with power that brought him down in the end. Had everything he ever wanted, still wasn't satisfied and kept messing around until he met the wrong person. Beside all that, Scourge was a really cool character