If this was to be done, you'd have to have a limit to the amount of allies that a player is able to have, so that they don't try and ally with everyone, or all the high level players.

Also, if this was to be done, you'd have to have ally requests effective on both profiles. Say someone sent me an ally request, and I accepted. At the moment it would only come up on his profile as allies, I'd have to send the guy a return to get him on my profile as my ally. If you changed it so that once an ally request is sent, it's effective on both players immediatly, and also had the quota of allies that a player can have, then you wouldn't get people trying to ally with as many people as possible, or just the high ups, as the highups wouldn't add them due to the quota, and the player could only add a limited amount of people.

I think DL's idea is a good one, but new boundaries, something along the lines of what I've just written, would have to be added.