Interesting bit of history. I still don't understand why the basement, (obviously some work has been done since the buildings construction) , would not increase the value of leasing the property. Not by some huge degree but it is still a viable storage area at worst increasing the sq/ft. of the property?
Unfinished brick and mortar area or finished in some form to be in a useful state it would affect the value of the property similar to other properties used for commercial or retail purposes. You could even use it as the "Deep down, Rock Bottom price Cellar".