This is a common form of asset ownership between spouses. Joint Tenancy (or TBE) has the advantage of avoiding probate at the death of the first spouse.
However, the surviving spouse should not add the names of other relatives to their assets. Doing so may subject their assets to loss through the debts, bankruptcies, divorces and/or lawsuits of any additional joint tenants. Joint Tenancy planning also may result in unnecessary death taxes on the estate of a married couple and loss of control over the ultimate distribution of the estate.
For these and other reasons, a Living Trust is usually the preferred estate planning vehicle.