Kikiyo's soul
If Kagome is Kikyo reincarnated, why did Kikyo's soul not return to her once she died?
Nevermind. I think I have it. Kikyo was able to redeem her soul (made up of malice and regret that remained in the clay body). To then have it merge with Kagome at that time would have underscored her accomplishment, which was to reach Nirvana, rather than simply willing to be reabsorbed. Sort of like being accepted into Heaven versus entering another person. The former definitely projects more of a theme of forgiveness and redemption. Also, Inuyasha said it in The Final Act...Kikyo's greatest wish, beyond being with Inuyasha, was that she didn't want to fight anymore. She spent her entire life fighting. Had she gone into Kagome, she would have continued to fight. Whereas she was able to obtain peace at last.