Actually, Chicken Pox can have LONG-lasting health effects. The same virus that causes Chicken Pox can resurface later in the form of shingles, an extremely painful condition that causes both a rash, and also affects the nerves under the skin. My Mother got shingles a few years ago, and the nerve damage caused by it still causes her pain.
Also, for older kids who have NOT had Chicken Pox, the effects of the virus get worse the older the child gets. For teenagers and adults, Chicken Pox can cause permanent scarring, and the fever can be life-threatening. Ask my brother, who got it the week of his 15th birthday.
Now, I don't get the seasonal flu vaccines, and I probably won't get the H1N1 shot, either, simply because I haven't had the flu in almost ten years. However, I think it should be pretty obvious by now that some people (pregnant women especially) are at such high risk from this strain that they absolutely should get the shot.