The purpose of a will is to distribute your assets at your death. It should address guardianship issues if incapacitated individuals or minor children are in your care. A pour over will is just a different type of will. It transfers assets to your revocable living trust, which will distribute your assets per the trust agreement.
The goals of establishing a living trust are to streamline the distribution of assets and provide a degree of privacy for your beneficiaries. When assets are allocated in a will, the will goes through a public process in the probate court. Anyone with an interest, benign or malevolent, can view the will and its contents. You may not want to reveal to the world that Aunt Jenny just got fifty thousand dollars. She might not want the attention. Assets that are distributed by a trust are private. It remains Aunt Jenny’s secret, until that time she sees fit to share it.
Assets in a pour over will are distributed to the trust after the probate process. Probate is usually rapid with pour over wills. Fewer assets are involved and therefore less steps are involved in reaching the end of probate. Most assets have been transferred to the living trust in advance.
It is not uncommon for items of lesser value to be left outside the trust. The pour over will sweeps up any stray items to be included in the trust. Once the trust has control of all assets, they are distributed by the guidelines of the trust agreement. Once all assets are exhausted, the trust is dissolved.