People stand and take off their hats to show respect to this great nation and the people who have died to protect it, in the same way that the national anthem is treated. I don't see a problem with it getting the same treatment as the national anthem, both are signs of respect. It's also kind of old school, such as taking your hat off when eating or escorting your woman out of the car.
The national anthem isn't sung by people out of respect, and to contemplate how lucky we are. Also, to appreciate the talent of the person singing it (i.e. if you were singing, you wouldn't be able to hear the singer). It's a more serious, pensive type of thing. Whereas TMOTTBallgame is sung when you're 4-6 beers deep, happy to be at the game, and having fun. It's a singalong karaoke song. The national anthem isn't.