I think this really isn't fair to the airline. The article was from one woman six years ago and it wasn't even really Delta, it was one of their smaller carriers.
I've flown many times with both of my daughters as babies and I have never had a problem nursing without a cover. It has never been an issue for me. I think that no matter what a company's position or commitment to allowing mothers to nurse, there is still the possibility that an employee won't act in accordance with policy. If an employee fails to act in accordance, it should be brought to the attention of the company and they should fix the problem. There was recently an issue at Target, who is very nursing friendly.