I decided that changing STUNNED to "You may only take 1 ACTION and no REACTIONS on your next turn, but do so as a SLOW TURN." I think this accounts for your valid point about how fun-sucking it can be to lose your turn, but also keeping the status as something impactful. Being able to take a single action keeps you in the fight, but losing a reaction and going on a slow turn makes you think twice about what you'd want to do. If I were playing, I'd even use my action to take a stance!