User blog comment:Xilinoc/Ch. 676 - Horn of Salvation/@comment-24769684-20160602134941/@comment-26091912-20160602142227

You do realize that Bleach is a character-driven series, right? Therefore the plot would be character-driven.

In this case, Ichigo is now able to access the power of his Hollow without going berserk, but can't access it by force of will, and can now fight Yhwach on even ground (sorta). Development, advancement, you can even call it a 'plot-device' or 'deus ex machina' if you really want, whatever.