As estate planning and probate lawyers, we occasionally have clients who come in, chat with us, fill out our estate planning questionnaire and have us prepare draft documents for them - and then never get around to actually executing the documents. The reasons vary - sometimes a husband and wife can't agree on who should raise their kids if they die in a common accident, sometimes they just never "get around to it". One of the saddest, most frustrating things we encounter is the call from the widow or children of a client, informing us that the client has died, when we have to tell the caller that there's no signed will because the client didn't follow through. It happens more than you might think. Although there are still ways to handle the estate of a person who didn't have a will, it takes longer, is more complicated (and thus more expensive) and creates unnecessary headaches for all concerned.
The same thing happens with medical powers of attorney, statutory durable powers of attorney and directives to physicians ("living wills"): when you've had an accident or a stroke and you can't communicate with your healthcare providers, it's too late to fill out a medical power of attorney. When your mom is suffering from dementia and you need to handle her affairs, it's too late to have her do a statutory durable power of attorney.
Do yourself and your loved ones a favor: sit down with a good estate planning attorney and talk through your options, then follow through. They'll thank you for it, even if you're already cavorting in heaven and can't hear them by then.