The purpose of explicitly disinheriting people is to ensure they don't get your residual estate by default if you *and* your beneficiaries die. e.g. my spouse and I have no children, so our beneficiaries are my spouse's siblings. It'd only take a family reunion and a freak car accident to take out all the named beneficiaries. To resolve that we'd either need a really lengthy list of backup beneficiaries, or just explicitly disinherit my douche canoe immediate family and say "IDGAF" after that.