At this point, it is clear, that many people are unhappy with the current reaction system and its inflexibility.
I may toggle the shield spell on to protect my fragile wizard, only to get attacked by a weak goblin, block the attack, and then not be able to do anything against the big minotaur hit that comes next. Effects like cutting words have been buffed to circumvent this problem to stay for the entire turn, but the issues remain.
Many have as a consequence asked for an active reaction system. After every hit from the Paladin, a pop up menu comes down, asking you if you want to smite. For bards, there are pop up menus after every attack roll, skill check, saving throw etc.
That slows down the game substantially.
Here is my proposal:
Bring back some real time with pause elements. You can either toggle a reaction on so that it automatically happens if the conditions apply (if a wizard is hit, cast shield), OR, as the default mode, assign one button as the reaction button.
If the enemy attacks my character (or any other action happens), while the animation plays, I can press the button (space for example) and the animation stops. Then a pop up menu comes down with all the options for reactions.
Then, I do not have to click away a smite (y/n) pop up menu after every single hit, but only if I choose to smite. Bards do not have to click away a reaction menu after literally anything that happens, but rather, they can flexibly decide what ability check, attack roll etc they want to apply their inspiration to.
This avoids both the issue of the game slowing down immensely, but keeps the flexibility of the reaction system of a game like Solasta. This would also allow Larian to implement the reaction abilities (cutting words etc) as they are in the PHB without having to change them to rebalance them.
Tl;dr:
- Assign one button as the reaction button
- If you press the button during an animation, a pop up menu appears with all the possible reactions
- Keeps flexibility and PHB faithfulness of a game like Solasta, without being drowned in pop up menus
- Might even make some BG purists, who complain about the real time with pause system happy

Let me know what you think!
Good compromise for Larian?