I read the article and have some mixed feelings about the authors points.
I will call a coach by first name, but only if I have a relationship with
both coaches involved in the contest. I'm damn sure not going to introduce myself to a coach I don't know with a "Good afternoon, Coach. My name is Andy", and go over to the other coach that I do know with a "Hey, Joe! How are ya?, Good to see you!"
I don't mind being called by name on the field, I guess that is just a personal preference.
As I have started doing more college level ball the last few years, I have noticed that the college coaches seem to like calling the umpires by name. I think they do it for just the reasons the author of the article suggests; they think is establishes a more personal relationship and your calls will go their way more often.