Wild guess was that they didn't want a tilted game to be able to replay balls. Since there were no replays or other payoffs on the machine directly, might be a way to prevent a casual looker from thinking you put together a super good hand by cheating.
Of course, you could always lift the front legs and drop it to get the balls to move...
Yeah, definitely seems like a solution in search of a problem to me. Similar to a lock relay, since it is powered at all times the game is on, that coil is going to get cooked eventually. Weird that they spent the money on that and a custom armature to block the hole.