User blog comment:BlazeUchiha/Have Bankais lost their Status?/@comment-452405-20100403061842

We don't really know the full extent of Ichigo's bankai abilities, as for one he's only been a shinigami for a year or less. Urahara is the only other to learn his bankai using his 3 day method but he did that over 100 years ago meaning he's had time to learn and develop his power.

Renji is the only other character to learn bankai recently and we can all see that he isn't all that powerful or confident with it yet as like Ichigo it is knew to him and hasn't been fully developed.

It's true what you say though, I believe if Byakuya had hit him with Gokei, Ichigo wouldn't of walked away whistling, but Byakuya has had the years of development to gain such an ability like Gokei, I doubt he had the technique the moment he gained bankai.

Give Ichigo and Renji a couple of years and I'm sure they'd fit into Byakuya's description with new techniques and power to match.