Allows you to have one decision maker (the trust) to control all of your assets.
If the Trustee needs immediate liquidity, they have access to funds. Ensures beneficiaries receive from ALL assets.
In the event you outlive a beneficiary, if assets are left in a trust instead of to an individual, and that person predeceases you, the money is distributed according to your wishes.
Avoids differing results on forms from financial institutions. For example, if some children survive and others don't, it can have the effect of unintentionally disinheriting the children of a deceased child.
You get to be as granular as your heart desires about what should happen in the future. You can control what happens no matter who is alive at the time of your death.