@Tokoro:
Honestly I was just thinking the same thing. I mean, think about it: there really is no precidence or reason for all of these super-uber powers to exist in this universe. In OP, it makes sense: you live in a dangerous world where everything is trying to kill you from pirates to animals to who knows what so you have to be prepared to go forth. Even in Naruto there is precidence: you have no idea what sort of enemy or ninja you may face in a mission so you have to be prepared. But in Bleach…that was originally just "death gods vs. simple monsters", the super-uber powers started with Bankai, the Arrancar and Espada were even introduced just to give them a reason to use said power...and with the Royal Dimension already showing haxxed power without properly being introduced without hints...yeah, it's just an arms race for power instead of given a reason.
To be honest, the Captain Squad's strength never bothered me. Bankai marks the line beyond which the character enters the realm of the strongest. The thing is, we were expecting some kind of power hierarchy since the soul society was first introduced ( and by that I mean the time when Renji and Byakuga came to retrieve Rukia ). Actually such a hierarchy is fine as a plot device. When it was first said that only captain lvls can defeat a Menos, we understood the difference in power between a normal shinigami and a captain. And that's fine. It all went downhill when Ichigo's friends could not do anything (except for Ishida, who's battle with the crazy clown-doctor still remains the best battle in Bleach's history ), the dialogue was disappearing and captains in a period of days gained a 50lvl power-up in order to defeat Aizen's organization when some of them were earlier depicted weaker against others. First example is the kid-captain with ice powers and then all the wins against the top 10 vast-lords.
On the other hand, the hints about Ichigo's hidden powers were shown pretty early in the manga, so we can't blame Kubo for the Masks :P and that kind of power up. That organization proved to be a failure after all the planning and the secrets and that is were Kubo fails among other things. Ichigo's biggest secret and power-up and it did not make any actual difference. All the captains handled their opponents with just a bankai.
What disappoints me the most is that for the last 220 chapters the only thing we see is battle after battle, no plot development, favourite characters buried in the mud(when did we last see Chad and Ishida ????) and overall boredom.
Sorry for the general rant btw…