Honestly I respect the choice to make Asami and Sayuri's routes mutually exclusive, if people are that desperate to see them both in quick succession, that's what the gallery's for
How does that add anything to the story?
With that course of action, you're only locking out a character. I can 100% bet that nobody would have thought much about it had it not been included or said so by the author and would’ve been equally enjoyed by the players.
This choice only leaves a sour taste with a feeling of "What if?!"