I do random game night twice a month. All my games are in a database, I hit the random button, and play whatever comes up. If I have people over, we turn this into a scored competition. Did you know Molly Hatchet performs the title song to NASCAR 98? My friends and I do, because it was the final game of our random game night challenge last week.
If I had to get all my systems out of a box every time we played a new game, that would be awful. Sure, most people don't do random game night challenges, but most people don't know how much fun it is either.
...plus, now I know I could kick all your asses in NASCAR 98.