In a nutshell, not probating an estate is a really bad idea. In many cases, but alarmingly not all, there is usually a will that has been left by the person who has passed away detailing how the estate should be distributed. However, the probate process is the actual legal review and confirmation of the will in a court of law. If a will and its estate are not probated properly within the expected amount of time, that will can then become useless or invalid. When this occurs, the court can flat out decide how to distribute an estate to whomever it deems appropriate, including non-family and parties that were never mentioned in a will at all.
It is recommended that at least once a year, or when you have a major, life changing event, you review your estate planning documents to ensure that they are in order. Changes that occur within your life can cause these issues to be dated or no longer relevant. Here is a checklist that you should follow when determining if your legal affairs are in order.