Originally Posted by
Reynhart
If F&C procs new NewJump in place of Jump, on the condition that jump is used, you can feel forced to use Jump to have access to NewJump, and perhaps you'd want to save Jump for a little later...but that later might mean you can lose the NewJump proc, if it takes too much time. You could end with suboptimal situation by linking abilities that have no relation whatsoever.
By keeping the combo chain as the only "procs" you change nothing on the current dynamic (Well, except, maybe for MNK), since you never want to use a 2nd or 3rd WS by itself, and you also never need to reset the same combo.