Well, the centroid "moves" with the increasing number of finds, so how informative would that statistic be?
E.g. you usually cache in your homezone only and have the stats you wanted showing you the caches within 5 km to the centroid.
Then you go on a trip far far away and find a number of caches there. Then the centroid will move some more oder less big distance and the stats may be totally different or even empty because you perhaps did not find any cache in the 5 km radius from the centroid..
Just an example, how the movement of the centroid could affect those stats..
