Exnewsman - Keep in mind what a big box retailer is usually most interested in - the bottom line.
By knocking down an old building and starting from scratch, they know exactly what that will cost. By trying to renovate an old building, they will be working with a huge unknown as to how much they will spend as there can be some massive structural, plumbing, and electrical costs that could easily make the project come to a halt (20 West Adams as an example). Plus, by building a new standard store, they have tweaked the prototype design of the store in order to most efficiently utilize every square foot. If they renovate, they will lose all of those efficiencies and have to pay more money for a new design.
With all that being said, hopefully the retailer will realize that the public wants them to renovate and not demolish. The main way they would not demolish is if they realized that they would be causing an uproar in the community if they went through with it.