There is a group of people in the UK who carry round a bunch of little cards advising that the music playing at the place they went to, be it a shop or mall, or whatever was inappropriate and ruined the ambience. I can't emember what they call themselves - an old girlfriend's mother was one. That you, Park?
Music enriches the soul. It lends a certain atmosphere to an environment; at the museum we used to put appropriate music on because without it, you had hangars full of aeroplanes, which was a bit eerie for people when all they could hear was their own footsteps echoing off the floor.
In my experience, I've found that airshow music helps create an ambience, because, as most of you pointed out, you don't want to hear a commentator droning on all day, not only that, but it makes up for 'dead air', which can be equally dull if there is nothing going on between flying displays.
I remember during one memorial airshow in the UK I went to, I can't remember what anniversary, but they had the Battle of Britain Memorial Flight Spit, Hurri and Lanc doing a display with Elgar's 'Nimrod' playing. I tell ya, there weren't too many people without a lump in their throats after that.