So, at the moment removing your old base does not remove purge points, to me it seemed that it just increased.
So atm there is no point other than improving server performance, which is poor motivation.
Perhaps make it so removing your base will decrease the purge meter. For server performance and for people like me that enjoy exploring but is now stuck with 3 half finished bases without any defenses and over 75% on the purge meter. and i am solo.