There's a rumor about impending doom in each province. I was playing it A LOT a couple of years ago. I remember the summerset isles one and also one about a plague in valenwood.
Yeah, Arena can get really addictive. It can be repetitive, but it's so fun to travel from village to village all around Tamriel, buying an ale and picking up a quest, then moving on. And the dungeons are intense. I remember having to give up on the one in skyrim and go back to leveling.
I use Arena alot if I want to name a new character in one of the other two Elder Scrolls games. I go to the home province of the race of my character and ask people for their names to get ideas.