It's a busy world. Everyone trying to outdo each other by advancing to the next level.
I was reading the manga recently, and something struck me. Anyone remember Byakuya's description of Bankai?
He says that even out of the Noble Families who are blessed with greater Spiritual Power than others, only one person in a few generations is capable of acheiving Bankai. It is the final release of a Zanpakuto and increases the wielder's power around 5-10 times greater than original. IT is a revered phenomenon which takes years to acheive and master and those Shinigami capable of Bankai always had great roles in the history of Soul Society.
Now I'm pretty sure Renji doesn't have a recording of those words and even if he did, he certainly has never listened to it. And Ichigo? What Kuchiki taicho said is probably long forgotten.
What's this about youngsters wielding Bankai and achieving it in three days? Is Bankai just another showpiece for every Shinigami? I think there is more to that.
Take into account those who have mastered Bankai the traditional way. There is a reason why it takes so long to master Bankai: because all that effort is what ends up paying off as the immense power Bankai possesses. Thus, all those who have done it the good ol' fashioned way are always much more powerful than those who have not (with the exception of Urahara, who undoubtedly, has a powerful Bankai).
Take Ichigo now. Ichigo is said to have nearly twice the reiatsu(forgive me if i use the wrong term; i'm kinda new) of an average Captain. He has combated powerful opponents and overcome them. But was it because of his efforts alone? I can't find a single instance where he has fought an enemy without a cause to fight for. He has never done it for the sake of doing it. Of course, the situations demand varying actions. Now compare Ichigo's Bankai to ,say, the power of Shunsui's Shikai. Personally, since Ichigo's Bankai is mostly melee type + Getsuga Tensho, I think it wouldn't even stand a chance against Shunsui's Shikai. The thought of Shunsui's Bankai doesn't even occur in the frame. I know I am comparing Ichigo to one of the more versatile and powerful captains, but consider even a Captain who is one step below, i.e. Byakuya or Toshiro.
Byakuya used Senkei against Ichigo but said that all the blades would not attack at once, thus providing Ichigo some chance of resistance. But what if Byakuya had used Gokei instead? Gokei is a technique that allows for all the fragments attacking from all possible angles all at once. Would Ichigo have stood a chance, whether hyper speed combat or not?
I know Ichigo has never truly fought Toshiro (they had a skirmish in the second movie). But lets say that they went all out with Toshiro unleashing Daiguren Hyorinmaru. If Toshiro had used Hyoten Hyakkaso, I doubt Ichigo would be laughing. Some might say, Ichigo is fast enough to move out of the falling snow radius. But consider this, surely Hitsugaya is skilled enough to constrict him and keep him there?
Bankai is a powerful force to reckoned with and I personally feel it is not given the austerity it deserves. To wield that kind of power is unreal and those wielding it (properly) are powerul foes.