Someone just pointed me at this excellent article on the RealSimple website (I love that magazine). I thought it was so dead-on that I had to post a link to it here: http://simplystated.realsimple.com/life/2008/03/unforgettable-a.html
There are almost no professional portraits of me from my growing up years, save for my annual school portraits, which of course are awful. There's one professional portrait of my whole family from when I was in the fifth or sixth grade, and boy is it boring! It's not that my parents were negligent, it's just that it probably never occured to them to have professional portraits taken. It just wasn't done all that often. Things have evolved so far since then! These days people have recognized the value of having wonderful portraits of their kids. They grow so fast! But it's not just kids -- a good portrait of any loved one, no matter what their stage in life, is a thing to be cherished.
It's so nice to see my work hanging on the walls of my clients' homes. I always ponder the importance of these images. A truly good portrait transcends the generations, and I'm not talking about a stiffly posed group standing in front of a painted library backdrop, I'm talking about images that show togetherness and reveal the personalities of the subjects.
I agree that random family snapshots have their importance, and everybody's got a digital camera. But there's no substitution for an artfully captured professional portrait. Hire a pro, spend the money to get someone who knows what they're doing and has a photographic style that meshes with your aesthetic. Someone who understands light and has the instincts and experience to capture your loved ones beautifully. You'll be glad you did!