Here's the thing about Kubo:
He always gives himself a backdoor so that he doesn't have to commit to any decision he makes. He'll start to go down one path, then he'll get nervous and back up. It's like he's saying in his head "I'm gonna kill him! I'm gonna do it this time...nononono, abort! ABORT!! FUUUU-" .....And then he runs away like a bitch.
I love Byakuya to an unhealthy degree, but what Kubo did was worse than killing him. Byakuya's personality and reputation was dragged in the mud. He was destroyed by a no name Nu-Quincy, then was made to beg and snivel as a plot device to pump up Ichigo. He was denied a decent death, and that really pisses me off, primarily because I don't think Kubo has the skills (or time or patience) to properly show the angst that Byakuya would naturally feel after such a weaksauce battle.
Even Yama-jii's missing body gives Kubo-troll an out if he wants to bring him back.
Plus Aizen's very existence gives Kubo the option to reset any portion of the manga he so chooses. Think about it. Don't think he wouldn't do it!
Also, I laughed my head off at the reason for the 4th Division sitting on their collective asses. All concentrated in a single building. Not even on standby. Are you serious!? Juha Bach could have destroyed the whole building oneshot style, and whoops, all the healers would be soul dust. Army medics in real effing life go out into the field when needed. They have military training! And these are humans with guns, not the several hundred year old superpowered beings the Shinigami are supposed to be.
Hey Kubo, guess what? Healers are useless if they allow everyone to die! Amazing!