It shouldn't be difficult to program at all.
What it would be is potentially incredibly annoying if the player is being constantly prompted to take reactions or not for every character all throughout a fight. That's the annoyance they're trying to avoid. They want combat to be smooth.
That said, I agree completely with you. The way they have it implemented now is crap. Maybe let us "opt in" to the specific reactions we want to be able to decide on and ignore the rest? I get where they're coming from with wanting to avoid spamming the player, but this "solution" doesn't solve anything.
