I can tell you about the '84 celebration, having witnessed it first-hand.
Though, I missed some of it because I had to wash the blood from my hand and try to stop the bleeding, due to slipping and falling off the damn light pole. I did take advantage of my being temporarily stuck in the Shell gas-station garage (where they let me use their fawcett) across from the stadium to call home. I remember my father telling me that there was a riot going on down there. I looked out the window and confirmed that, yes, there was a riot going on down here. I also said that I'd have to stay here awhile, because my car would have to cross Michigan Avenue, and I didn't want my car destroyed.
Anyway, I wonder what I could get on Ebay for eighteen-year old outfield turf and a couple of light bulbs taken from the left-field auxilliary scoreboard that night.
But, as far as I could see, the damage was limited to a few cars, and a lot of "disrespecting" of Detroit Police who were trying to end all the fun. There were no busisess that were looted or anything like that.
But, to answer your question, I guess I have no idea why fans would behave like that. I know I never would (again). I guess it's just that a few idiots can really make a big show and ruin the reputation of the whole group.