That is in order to provide a wide base for the tall thin support column. Without the base the thin column has only a tiny area attached to the bed and will wobble or could be dislodged and fall over when it gets to the higher layers (like balancing an upright pencil). Not sure why it is any harder to remove - the skirt is on the bed and so makes no difference to how easy it is to remove from the print.
Dave
Edited 1 time(s). Last edit at 01/28/2015 10:25AM by dmould.