I just had to join to reply to this
I think if you stopped being biased, You'd realize They did fight to kill so they could capture. You can see how that turned out now can't you? Sasuke being almost killed. Twice. I think Killed is better than almost killed because without Jugo and Karin he was dead. Suigetsu saved them all from death. Sasuke just failed. Amaterasu from the start would have failed also. Killer Bee was definitely fast enough to avoid Amaterasu's flames. Killer Bee was playing around with them. He had the upper hand, He just changed into the 8 tails just cause he got carried away. If he continued with the cloak he would have killed Sasuke.
Sasuke isn't the ultimate character in this series. He wasn't even supposed to be in it. He was only put in as a role of the rival for the main character. Kishimoto's editor told him to put a rival in so Sasuke came in. There was already a Naruto planned out without Sasuke.