Crime (mainly thievery) a subject that people always wanna duck and dodge, that's the main reason. Crime, and perception of crime is the top reason that most malls fail.
I've saw far worse than Regency around the country. Regency definitely have seen better days, but I wouldn't call Reg dead just yet with a core in the East Mall, and three anchors still open. Wanna talk about dead? Try Global Mall at the Crossing in Antioch, TN just outside of Nashville, with zero anchors (again, crime was the factor).