The only thing I can say for certain was that Kubo was rushed when it came to the ending of his series.
Of course the story was rushed I have never denied that but let face it unlike with NS. IR was acknowledge as popular. Shueisha had kishi go with nH because they thought it would make them money. Other the other hand they just wanted Bleach to end so they could add another series to the magazine. They didn't care about pairing they just wanted it dead. So it was kubo choice to go with IO and RR. Whether for good intentions or not and at least his didn't come off as depressing and negative.