why does a will have to be probated

If there are assets which became part of a deceased person's probate estate (i.e., assets which did not become another person's property either through the operation of a right of survivorship or under a beneficiary designation, which would include many assets on which the deceased was the sole owner and possibly the deceased person's share of jointly held assets, if the assets were not held by the joint owners as "joint tenants"), then the Will must be admitted to probate in order for an Executor to be appointed, or the assets will just be stuck in the estate. In order for title to an asset to be transferred out of a person's probate estate to a creditor, heir, or beneficiary, a representative of the estate has to be appointed and take the appropriate steps. Title does not just magically transfer.