Being that ONT is my home airport, and I go to Chicago 3-4 times a year, I agree. The problem is that DIA is smack dab in the middle of the route. You can get to Minneapolis, Atlanta, and New York non-stop but not Chicago. I have always wondered if there was enough demand for this route. Certainly as the area continues to grow it becomes more likely. But in the end hub-and-spoke is to blame.