Major Speculation alert:
I always thought the rapid aging was to cover for the fact that the "War Without End" plot was supposed to be the series finale. 20 years into the future, Sinclair has a chance to take B4 back in time. To come full circle after the battle of the line, and actually becoming a Minbari - Valen.
That's always been my speculation about JMS' original plan. It makes sense... IMO
I always thought the rapid aging was to cover for the fact that the "War Without End" plot was supposed to be the series finale. 20 years into the future, Sinclair has a chance to take B4 back in time. To come full circle after the battle of the line, and actually becoming a Minbari - Valen.
That's always been my speculation about JMS' original plan. It makes sense... IMO
