When you 'update' it lists the server with the lowest ping at the top. However this is never an accurate ping, only when you refresh do you get an accurate ping.
This is important for two reasons, from a self-interest position i want people to play on my server, but if newbie European players are seeing it halfway down the list, or people are seeing it with a 200 ping when it should be 40, then its unlikely to be played on.
The second is for new players who, i presume, would pick the fullest servers near the top. Imagine someone from the US going on an OTB server with a 200 ping, more than enough to put them off the game.