Vacant apartments, apartment buildings, and even cities full of them are due to some sort of Chinese preoccupation with apartments that haven't been pre-occupied. A standard Chinese apartment is a concrete shell that needs flooring, interior doors, and often even the electric wiring installed. A "virgin" apartment in this state is considered to be more valuable for resale that a "decorated" apartment that's ready to live in.
No, I do not pretend to understand the logic of this. It's just the way things seem to be.
"Redecorating" in China doesn't mean changing the drapes and getting a new sofa cover. It typically employs things like chisels and jackhammers.