Les, I'm a bit unclear what you're saying. From your comment about SE sides dancing Border you appear to be suggesting that sides should only be revived where there was an original tradition to draw on (as in the case of Gorton).

Given that morris appears to have once been widespread throughout the country, it seems unlikely that there weren't once traditions from the SE, unfortunately most of them haven't been recorded (although IIRC there's a dance from Herts in the Black Book). So why shouldn't new sides start up, and dance whatever they want?

If you come from an area with a recorded tradition, then it is likely (but not inevitable) that you will want to retain that local connection, but if not there is no reason not to dance whatever style takes your fancy.