i remember a lot of BF42 servers had trackers for their servers somehow.  not too sure how it worked.. but it was only tracked on that server and you could see the stats at the clan website or wherever

Medals would just take away from the general fun of the game because players would be worried about their stupid stats rather than having fun.  Plus ranked servers cost a lot, and the work put into a medals system might be in vain if there are a lack of ranked servers.

A ranked server would cost no more then a non-ranked server, if they implemented their own ranking system.  However, you would just need an extra server to send the player statistics to.  At least, that is how I think it works.  I could be wrong entirely. 

Or, it could be server-side, so the server you are on stores the player data, meaning you would have different ranking and such in the different servers you go to. 

In my opinion, there should be a ranking system, but not neccessarily by points.  Rather, perhaps people get voted into the position by the common players on the forums, then get the nice little shiny badge in-game.  Not that it really does anything.