The way I see it, athletics as spectator sport serve two main purposes: inspiration and affiliation. It fails to provide either.
It's always good to see what humankind is capable of and what it can aspire to. The four-minute mile is a great example of this: Roger Bannister was a medical student. He trained, studied, trained, studied. We should all be amazed at what he accomplished. Likewise, when I attended diving competitions to see my brother compete, I watched people dive from 10 meter platforms and perform various contortions on their way to meet the water below. We, as humans, are capable of many things, and it is important to be reminded of that so that we continue to strive towards our own goals.
My argument here is that professional atheletes cannot serve as inspiration because they are no longer human. Professional atheletes are filled with steroids and other performance enhancers. Compare Roger Bannister, medical student, to Carl Lewis (stimulants!) or Ben Johnson (steroids!). That's why, I think, the leagues and associations are against drugs and cheats (Howard Johnson's corked bat, for example). Cheating doesn't inspire us. Even the characters that aren't pumped full of dope, in the highly-paid sports, are millionaires who can train all day, every day, if they so desire. These people have nothing in common with us. They live in another world, and can no longer inspire us. Their struggles are not our struggles.
Root for the home team! People enjoy watching team sports because they feel an affiliation for the team. In high school sports, you feel that affiliation because the players are your peers, your family, your neighbors. The bonds are close. They are people that you know. In college sports, that can still hold true in some respects, although in big money sports like football and basketball, I have to wonder. How many football and basketball players did I share classes with? None that I know of. They were not my peers. I didn't know them, I didn't know people who knew them, I didn't even see them on campus.
Professional sports hires the best players they can for the money. That means they come from all over the place, and the home team isn't really from your home at all. The best, and by that I mean the most conscientious, players make a point of trying to integrate themselves into the community, but since they might be traded at any time, what real incentive do they have? They are nothing but mercenaries.
When we feel affiliation for a professional sports team, it is mostly by proxy. They are associated with the city I live in or near! The players appear frequently on my local news channel! Other people that live around me wear the team logo on their clothing!
Both inspiration and affiliation are important, but professional sports fail to provide them because they are neither of us nor among us.
Feel free to offer a counterpoint.