Making vegetables (those with leaf) more "crunchy" (bite/tear off easily)
Leafy greens generally tear quite nicely when they are raw.  If you apply any moist heat to them, they will wilt and no longer tear as nicely.  In fact, certain leafy greens can become downright tough if you cook them to long.

If you'd still like to cook your greens, but retain a little of their crunch, you can always grill them.