Having a last will and testaments are a recommended by all retirement and financial experts to make sure your estate goes to who you want it to go to and that your last wishes are respected. However important this is I believe that it is more important to make your wishes clear so that your family can have peace. All we have is family (children, brothers, sisters and grandchildren) and when the family is torn apart because you do not make your wishes clear your legacy is diminished.
Do not leave it to your lawyer, or notary to make your wishes clear, I have had people talk to me about how lawyers have misread statements built into last wishes, because they have only read what the words should have said, not what they actually said. One person told me that when they were acting as the executor of the estate for a family member, she realized that the wording in one part of the will actually removed the beneficiary from the will. Two lawyers read the will and both disagreed with her interpretation until she read the portion out loud to them and they realized that she was correct. The lawyers then charged the estate too correct the error they had made and overlooked.
If you are not clear on what you want to happen with your estate, the family may interpret your wishes in ways that you do not want and may cause your family to lose their connection to each other. It is up to you but be clear on your last wishes, you owe it to your family.