I played the Witcher too, but from the isometric view which wasn´t action, but more strategic.
What do you mean chance is already provided? If you miss an attack or a spell is interrupted and so on or depending on the skill you use, you still take a risk and it can have a detrimentous effect. If you play Vagrant S tory you´ll see what bad things can happen.
Depending on which jRPG you play, you can have direct or indirect input on stats.