I get them, only because I have both a kidney and blood disease. My immune system is shot and I have to get pnemonia shots and flu shots every year. The one year I didn't, I was violently ill for a few weeks, spent my birthday at the Royal Infirmary in Edinburgh. Not fun.
That said, I am a FIRM believer that (esspecially in the USA) people over-do the flu shot / antibiotics / germ-killing thing. Whilst I do understand the risks involved with certain groups of people who get sick, I also know that we are making our bodies weaker with the constant preventative measures. What ever happened to good old "healthy eating, vitamins, rest and excersize" idea? It works for me (mostly) and for my friends...
(Oh, and FunGirl, my Daddy had a flu shot ONCE in his life, because the military made him do it. It is the ONLY time he has ever gotten the flu. He will never get the shot again.)