Anyone can talk about something on stage. Not everyone can react to in-the-moment stimulus on stage. The few, the proud, the brave improviser reacts boldly in-the-moment to make-believe and taps into the art’s unique surprise.  The audience knows there’s no script to tell you how to react, so your reaction comes out of “your” perspective. The audience reaction of “I would have said that,” or “I know a woman who would have said that,” is such a satisfying response for any performance medium. In improvisation, that power is compounded as the audience knows that your reaction was “your” reaction in-the-moment.  Reacting to active elements on stage also give establish a foundation on which to build Personal and Scenic patterns and games, making improv more Pavlovian for the player and rewarding the audience for “getting it.”  If we’re not reacting, then we’re just talking.  And good luck with that.