Because people would visit it, like a football shrine. What I dont want to happen is the houston situation, the old Astrodome "7th wonder of the world" next door to Reliant Stadium, they haven't opened it up for years and cost the county $5 million/yr as it decays.
I would pay to walk around the old stadium just for the memories. I assume it will be torn down and used for parking, heard that before in Heston.