[norseboar]

It depends on why productivity is increasing. Generally speaking, the employer is pushing productivity increases (implementing better processes like assembly lines, buying equipment that lets an employee do more, etc). If the employer is pushing the increases, they need some incentive to do that.

Often that incentive is making goods cheaper, so they're more competitive. That's a huge generalization, but it makes the point that there's nothing wrong with productivity gains outpacing wages.