One of Bleach's strong points was the amazing cast of characters, however a huge problem is Kubo's inability to manage such a vast cast.
Now, I know that making comparisons to Oda would be unfair for any author, but think of the war of Marinford in OP, where he perfectly managed a huge load of characters without making it boring or turning a bunch of people into fodder.
In Bleach we should have seen a bunch of full powers already during the Karakura invasion arc, if he had made Hisagi and the vizards all use their bankai we'd have much less people that needs to be shown off now(and turned into fodder despite their amazing power they kept hidden).
Plus the Fullbringer arc was absolutely unnecessary and just added a bunch of characters that are redundant and just makes the battlefield even more confusing(and will make battles draw out longer..), when we already had an outside party that could come to support shinigami(the arrancars bribed by Urahara)
If all side characters had been taken care of at the right time he would have been able to make a final arc that focuses only on the main cast, instead here's what we need to see...
(starting from the main cast)
Urahara
Yoruichi
Sado
Maybe Orihime(dunno if she got a powerup, but I doubt she'll fight)
Byakuya's new bankai
and then we have all the shinigami crew:
Shunsui
Ukitake
Hisagi
Love
Yumichika
Zero Division guys
Grimmjow(maybe Nel too)
Fullbringers crew..
as an example of how Kubo failed to manage the characters think of Otoribashi's bankai reveal, steamrolled in 1 chapter, fodder ridiculousness.