I think that there is some utility for automatic reactions, but specifically as a setting which determines when you receive Solasta-like prompts.
I almost never want my Wizard character to use their reaction to take a swing at an enemy leaving melee range. But on the other hand I also don't want them to automatically counterspell a Fire Bolt from an Eldritch Knight when there's a full caster crackling with power who has yet to act.
I don't want my Rogue to spend their Uncanny Dodge automatically when moving past a caster, but I do want to have it when that Ogre smashes them.
I think a system which allows you to have settings for when you receive prompts would both cut back on excessive prompt spam, and still allow you to have a fine-grain control over the things you do want to save a reaction for.
