If you die without a will, your assets will go through the probate process. A judge will make decisions about how those assets are to be distributed, based on community property laws or state inheritance rules. In either case, these decisions may or may not agree with your wishes.
Also, probate can be an expensive and time-consuming process that exposes the details of your estate to public scrutiny. The probate process can take months or even years, depending on the size and complexity of your estate. And the fees charged by attorneys and executors can diminish the amount of money your heirs ultimately receive.