Well all the captains can justify all their stupid actions with this one simple truth, "They can't die!" Thats all it is. Shinji can give Aizen the whole 9-yards about his shikai's abilities and how to conquer it while still surviving the imposible. Shunsui and Jushiro can try their hardest to be dummies by holding back but will still live to see the light of day.
Soi-fon, Rukia, Byakuya, even totally unneccesary characters like Iba and Choujiro won't die. So as stated above, it is due to mostly PIS and the incesive need of monologue within Bleach that cause all of this to happen; this result in a form of pseudo immortality for the protagonists.
However would you give a damn if you knew you could survive everything the bad guys dish out? Maybe something lame like seeing Ukitake's bankai in a flashback will happen...I don't know.