Using anticipation can engage the viewer more, making them lean forward in the chair in (wait for it) anticipation of what's about to happen; it can also be used to surprise them, when the moment of anticipation tells them one action is about to happen only for the animation to take a completely different direction.
In a normal moment of anticipation, some slower action leads into the final punch. An example could be an animation of a cowboy lassoing a horse; before he throws the lasso, he twirls the rope in the air, building up speed and momentum. The twirl is the moment of anticipation; we know he's going to throw it, but we're made to wait a moment, to hold our breaths and see if he'll actually land the throw.
For a surprise twist, one example could be a boxing fight. When Boxer A draws back to throw a punch, we have our moment of anticipation - but we're thrown a twist when, out of nowhere, Boxer B lands his punch first. The moment of anticipation still has its culmination, but not in the result the build-up had implied.
Whether your result is expected or a twist, anticipation is a valuable method for involving viewers in your animation and making the motion seem realistic.