As far as most important arcade years, I agree that it has to be the early 80's, most of all 80 - 82. That was when the arcade busines took off and there was an explosion of stand alone arcades with a wide variety of games. By stand alone, I mean the only business they did was video games. In my hometown there were 4-5 stand alone arcades supported by only 20,000 people. Every retaurant, pizza joint and movie theater had a wide variety of games, if not a dedicated game room.
By the mid to late 80's arcade popularity dropped off drastically and never recovered. Computer games and game consoles started replacing the arcade experience and stand alone's went out of business or had to expand to other lines of business to stay open. Last time I was there, my hometown was down to only 1 video game place and that expanded to include mini-golf, a driving range, batting cages and go-carts. It's a very cool place, but very different from the warehouse that used to pound The Knack, Blondie & The Clash over an incessant electric babble.
Back then you could find your favorite game in any town no problem. Now if you want to find a particular video game, good luck. You have to take what you get by going to the bowling alley or a convenience store. And even then its probably just a fighter or two.