That was after Ichigo already defeated him.
Also, at this point, we're merely delving into "what could have beens". Basically, too many ingredients will spoil the broth. My argument this whole time has been that the story has always been critically lacking in focus. It's not a stretch to say that from start to finish, it's pretty much just been an endless series of detours. Giving extra focus to a character who was initially an irrelevant outsider does not really help with that.
Most of those middle-aged Shinigami weren't that relevant either. The bulk of them were just firepower and none of them were capable of dealing with the situation at hand.
Again, I'm aware that these characters are popular, but seriously, think about it. Among Ichigo's posse, there around half a dozen members, give or take a few. Then you have the Gotei 13, which is comprised of thirteen (or less) Captains, thirteen (or less) Lieutenants and countless other rank-and-file soldiers. Putting aside the lower-ranks, Soul Society alone has twenty-six (or less) characters to focus on. On top of that, there's also the Vizards, the Arrancar and the Quincy. It's a mess. Giving every single one of them a fight and a flashback is way, way too much. It's completely ridiculous.
I mean, as things stand, if you get rid of Chad, what, exactly, would that take away from the story? If you give the absolute bare-minimal focus to Soifon, Hitsugaya, Hinamori, Kira, etc., etc., how would that negatively impact the flow of the plot? You can't just introduce a hundred characters and focus on all of them. That's not what a reasonable storyteller does.
Focus. You show what needs to be done, add some fanservice within reasonable amounts, and that's it. I'm not saying that you should only put what's absolutely necessary, but if you're gonna add extra things, they should be used as a bit of extra spice or garnish, not dumped in wholesale.