I don't see a better solution to the reaction system
A tactics tree like DOA would never automate reactions better than the player just being given the opportunity to stop and choose.
It's not a solution to your wish for the reaction system to not exist. The entire point of a reaction, is to give the player the opportunity to break and "react" accordingly. If you don't want to be able to do that, a solution would be to have a toggle switch to disable reactions for that character.