In Dead Man's Chest, it is revealed that Davey Jones cut his own heart out in order to spare himself the anguish of his separation from Calypso, and that before he did this - and turned his back on his duty as a nautical psychopomp - he and his crew appeared as normal humans, not humanoid sea-creature chimera. This implies that the lack of a heart within the Flying Dutchman's captain's chest is not a requirement of the position
However, in At Worlds End, after Davey Jones is vanquished and Will Turner is dying or dead, Will's heart is cut out so that he can become captain of the Flying Dutchman and take on Davey Jones' former role as psychopomp.
Is there any explanation for this apparent discrepancy? How was Davey Jones able to serve with his heart still within his chest until his emotional trauma led to his removing it, yet it is implied that Will Turner cannot become captain of the Flying Dutchman and take on Davey Jones' role unless his heart is cut out?
Is this a plot discrepancy or is there a valid point that I've missed?