Yes. A will would be important for several reasons. You may have property that never got transferred to your trust while you were alive. You would need a will to transfer that property to your trust after your death. Or your estate might receive money after your death. For instance, if your death was the result of an accident, your estate may receive wrongful death benefits. Again, you would need a will to transfer this money to the trust.
You also need a will in order to name a personal representative and a guardian for your minor children. That’s not part of setting up a living trust. A personal representative can take certain actions on behalf of your estate that a trustee cannot, such as pursuing a wrongful death claim.