I don't like the reaction pop up windows in Solasta. They kill the flow of combat. I've also never missed a reaction mechanic in BG, NWN or any other crpg. Those games play better without constant interruptions or the tedium of having to toggle reactions on and off trying to guess how things will play out.
There's a simple solution to this in BG3. Bonus Actions. Larian have already converted many Actions into Bonus Actions because they feel players need more to do during a turn. So... convert Reactions into Bonus Actions.
E.g. Shield -> Bonus Action spell, +5 AC for 3 turns. AoO's can be automatic. Riposte can also be activated as a Bonus Action and be "active" until discharged. Active is the key word in using abilities rather than the passive toggles you forget about.
Knee-jerk reaction: I hate this suggestion.
But honestly, if Larian is going to keep in all their other homebrewed bonus actions (jump+disengage, eat, probably dodge, Land druids' wild shape, hide, dip, shove), then it wouldn't be the worst idea to change some reactions to bonus actions. At the very least, doing this will prevent you from always using Larian's overpowered bonus actions. I'd still prefer pop-up reactions, at least as an option.
3 things to consider --If these abilities do cost a bonus (or standard) action to use, then maybe they shouldn't use up your reaction as you've already spent the cost to activate them. --If these abilities still do use your reaction (and are either a bonus or a free-action to "activate"), then you should have some ability to choose targets to react to so you don't waste your reaction. E.g., Protection Fighting Style: you select a nearby ally, and if that ally is attacked you impose disadvantage. This prevents you from wasting it on a Tank who probably wouldn't be hit anyway. --I don't actually trust Larian to balance things properly if they make these changes. See all their homebrewed bonus actions and their thoughts why players don't like Bless, not considering how their surfaces and height/backstab advantage affect the usefulness of a concentration +1d4 to-hit spell.