the fact that a bunch of fodder Arrancars just came back to fight a bunch of fodder Quincies, despite being a far flung callback and a way to wrap up a current event, is not actually IMPORTANT to the actual plot of the series. Barring some shocking turn of events, of course. It's just a mop up job to deal with the fact that Kubo introduced another shitload of characters who all need to die. It's certainly a thing that is happening, but it's not IMPORTANT in the grand scheme of things. Because of the way that Kubo has set up the story, not a whole lot of anything is terribly important if it doesn't directly relate to Ichigo himself.