Lifehacker is running a great piece right now about why parents of minor children should have wills. The reason for making a will at that stage in life has less to do with the disposition of your property and much more to do with the need to make sure your childrens' guardian is clearly named in a document that will carry weight in court.
When both parents of a minor pass away, the event is already traumatic enough for the children and for the surviving members of their extended family. Failing to leave behind clear instructions about who will be responsible for your children in your absence can make things even worse.
The good news is that creating a will of this nature is not all that complicated. Most attorneys have basic will packages that provide all of the language that is needed to clearly spell out your wishes for your childrens' care should you die or become unable to take care of them yourself.
If you are a young parent, and don't have a will yet, I recommend reaching out to someone as soon as you can. It helps to have the peace of mind that comes from knowing that your legal issues have been handled, especially in these uncertain times.