We are so funny....
We want better discounts, but we balk at giving
DVC the sort of information they need to target them.
I agree about SSN, they shouldn't be asking, and even the last four digits shouldn't be showing up on the screen - unless perhaps your address doesn't match your member number - requiring some sort of identifying information to change your profile makes sense.
But they are asking your and your kids ages for marketing reasons....do people sell DVC when their kids leave home? Do they have a lot of empty nesters? Grandparents? Young singles? Should they market the next member event with events for toddlers and preschoolers? (A big gripe for me with the last one - we wouldn't have gone, but would some event starting before 9 killed them! - How about a special DVC character breakfast or lunch? How about an extra EE in Fantasyland? My preschoolers really aren't interested in fancy desserts at 9pm. But if there were a lot of young childless DVCers and DVC night at PI or the Boardwalk might have been fun.) When you bring guests, do you bring childless adults or adults with children? This lets them target marketing (which I don't completely approve of - spend your birthday in WDW! And we know when that is!), as well as discounts and events (which are the useful part of marketing).
And because families in this day and age are (unfortunately and fortunately) not completely stagnant, they ask each time. Maybe that five year old who lived with you last year went to live with her dad now? Maybe you've added a six year old grandchild that your daughter can't parent? Or stepkids? Maybe you've added or subtracted foster kids?
(Chuck, my DL nor SSN isn't on my checks. And I seldom write them, so there isn't any reason for anyone to write it down. I'm truly evil, I "help" them write my dl down on the check if they must, scrambling some of the numbers as I "recite" it. Also, when they ask for "a phone number," I give them exactly that - a phone number, not necessarily MY phone number, mind you.)