If you have a mortgage you need enough to satisfy the loan.
If you have own the property you need enough to satisfy YOU.
I could not find any company to insure my house in NC for less than 80% of rebuild. I, like you, would never rebuild the house in that area (I'd clear and sell the lot).
Companies are betting they will not pay for a loss so they want as much from you as they can get. IF you are willing to take the loss, you don't have to have insurance. You could just buy a liability policy to protect your other assets.