Yeah. I gotta agree. Pre-planning all your reactions is going to be a lot more of a pain in the butt in the long run, and for what? Just so you don't get a popup when a reaction could potentially be triggered?
I'm thinking about Passive Mode and Dual Weapon Attack right now with the game as is. I don't like to kill Mari and Barton and all their mercenaries. They're just treasure hunters. Ya know? They're not necessarily bad people. So, I set it to Passive Mode. Suddenly, I'm killing skeletons and later goblins at the grove, and I'm wondering, "Why are there stars over their heads? Oh yeah! That's right! I forgot to turn off Passive Mode."
The same happens to me with Dual Weapon Attack Toggle. Every freaking time I play the game, I usually have someone with two shortswords or daggers or whatever. And every freaking time I forget to turn off that stupid Dual Weapon Toggle. And now, it's a tiny button that's even easier to forget, and the difference between Dual and Single is so miniscule, it drives me crazy. And every single time, I waste at least 1 or 2 Off-Handed attacks before I remember to turn the dumb thing off - especially because every time it happens, it immediately jumps to another person's turn. By the time I get back to the character, I forget again.
My point is, Reactions would turn into the same thing. For my bard, I'd have to remember to play around with my Preset Reactions. "AOO on this target. Oh, and maybe this one too. Oh, and maybe this one. Okay. 3 targets for AOO. Now. What about Feather Fall? She has that spell, and we're fighting on cliffs, so maybe I should set that one too. But, if they shove me this way, I'll just fall onto a ledge 5 feet down. That's no big deal. Oh! But what if I get shoved more than 30 feet and fall off that side of the cliff? Okay, so let's set Feather Fall to 30+ feet, so if the game determines I'll fall more than 30 feet, I'll cast the spell, if I have the Reaction available still."
And that's just one character with nothing more than Level 1 spells. Imagine juggling 4 characters with all their potential reactions that you have to preset. And don't forget that although you preset them for this round, you have to do it all over again next round to make sure they work right. Why? Because the 3 targets you chose for AOO during the first round might not be the same ones you want to have trigger it during round 2, 3, 4, 5, etc. So, each round you'll likely have to play with the AOO Presets to make sure they are targeting the right enemies. I mean, Feather Fall you could probably always leave preset, but AOO, Shield, Counter Spell, Hellish Rebuke, Smite Reactions for Paladins, and other similar spells would just be a mess.
Yeah. No thanks. I'd rather have me pick my moves for combat and if an enemy comes within range to trigger my AOO, a popup springs up and all it says is, "Sazza triggers Attack of Opportunity. Use your Reaction to Attack Yes/No?" You pick No and move on. Real quick. It hardly even pauses the turn. Then Grick, the goblin, triggers AOO. Same message and move on. Bork, the goblin, hits you. Popup. "Bork has injured you. Use your Reaction to cast Hellish Rebuke Yes/No?" You pick no and move on. Nere casts Lightning Bolt. Popup. "Nere is casting Lightning Bolt. Use Reaction to cast Counter Spell Yes/No?" Click Yes and done. No more popups.
And, like Solasta, the windows could contain information for more than one person. "Sazza has triggered an Attack of Opportunity. Use your Reaction to Attack Yes/No?" But it shows an option for my MC, Lae'zel and Astarion, who are all within melee range of Sazza, to use their AOOs. So, I click Yes on all three and all three use their Reactions to slash at her before she leaves melee range. This would work with Counter Spell as well. Nere casts Lightning Bolt. My MC and Gale both know Counter Spell. Window pops up asking if I want to use my Reaction for Counter Spell. I pick Yes for Gale which immediately makes MC a No. In multiplayer, the first person to respond would be the one to cast it.
I'm sorry, but the more I think about Preset Reactions, the more terrible I think the idea is. Juggling them all is so not worth a smooth combat experience without pauses. There is simply too much to manage up front and remember each turn. I'd rather have no reaction system then to have to do all that work to preset reactions each turn.