This nonsensical logic where a player can attack you at will in the PvP Arena and you can't do anything about it, does that seem right?
Wouldn't it be fair if it was like in the neighborhood, where you have the possibility to fight back against that player who attacked you???
The counterpoint to this is that your points are only affected by the first 5 times you're attacked each day. Much like plundering, it feels worse than it actually is. And heck, you gain points if your attacker loses which is technically better than what happens if you win on city defense.
Send the player a friends invite. I dislike what you are seeing to from the other end. I would see only one person to fight day after day, week after week. I sent the invite then had to do it again with the next unlucky player. When you exhaust Inno's list of players you get bots to fight. Arena is another of the alpha's builds released to live.
This is probably indicative of a lack of players participating in the Arena more than anything else. Not surprising, since a relative lack of rewards, the active nature of the feature (having to actually participate to remain in the rankings), and an overall dislike for PvP in general is going to keep most of the playerbase out of the Arena. That said, I don't see how having it in harms the game, nor do I really consider it an 'alpha' feature when a lot of how it plays out is going to be community-driven. If more players were participating, there'd be more variety in opponents.