Lee Valley used to make a steel table top that was purposely raised at the center. The high center keeps a piece from bridging across the edges. The problem with a low spot in the middle is that a piece wider than the table will bridge across the edges but a piece will start to rise after it passes the bit and as the trailing end passes over the edge on the infeed side it keeps dropping until it gets to the bit. That isn't usually a problem except with rails and stiles, locking miter bits, T & G and anything where two mating pieces have to line up.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.