I'm just thankful people show up. haha!
I agree 100% with this statement.
As many have said, people show emotion in different ways.
Some people simply aren't the "Raise your hammers high" type of concert attendee, and are content watching from the back. (as Ken had stated).
I personally only go up front these days for bands I am really into or really a true fan of, where I want to pump my fist and scream along. (IE - Paul, "What song of the Knowing do you want to hear?" Jasonic - "Silent Tomorrow!!!!!!!!!!!!!!!!!!")
Just because someone is standing with arms crossed holding a beer doesn't mean they aren't going to buy a CD or attend a band's next gig. Sometimes people save their energy for the main band they personally wanted to see. (For example, I am sure there were a number of people who went to Powerfest just to see ATHEIST, and were saving themselves for that performance).
Larry - I know exactly what you mean about Slayer fans. I read a semi-recent interview with Kerry King, where he recalled the incident at the Aragon back in 1988 where Trouble practically got booed off the stage!!! It does leave an impression on a young kid. I was at that gig, and wrote off Trouble for a while simply because the Slayer "fans" were dogging them.
(When in reality a large chunk of that crowd was their to start fights and mosh!)