Definitely need the ability to decide whether or not to use reactions at the time they'd be used, not beforehand.
How do you propose doing that?
Every time you get hit, the game pauses for a pop-up that asks, "Would you like to use Riposte now?"
That would be the desire all 9 pages of this thread are about, yes. People wanting that to happen. For reaction spells, Riposte, opportunity attacks; all reactions. And it's apparently what they do in this "Solasta" game people keep mentioning.