Asuma.

Say what you want but I'm very confident that the reason why he was killed off is because Kishimoto can't write romance for squat so he had an opportunity to write him off. He couldn't kill off Kurenai because she was pretty much a useless housewife in Shippuden that doesn't fight anymore. It wasn't to make Shikamaru a more responsible person and besides, he would inevitably have to become a more responsible guy anyway. Kishimoto even said himself that he can't write romance well nor can he stand looking at real life romance, and it shows given how the ending of Naruto was. Fanfiction glore.
EDIT: So much for the spoiler tags....



This post was last edited by Sarutobi Asuma at 2016-10-3 12:15