Really? I think it explains things more and adds closure to something that needed an ending, not a continuation. Maybe he didn't have to because of the curse, maybe it was because his heart was actually stabbed. It was fatally wounded so he had to remove it. I dunno, I'm grasping. Maybe it was something that Davy Jones added to the burden. Since he cut his heart out, any new captain had to cut his out too because that was a new provision created by the previous captain..