The partition table must be recreated beause the geometry of the disk changes. In most cases users will not be able to access a partition created by ReactOS using Windows or Linux because of the different geometries. I tested the old geometry using gparted and it always reported a damaged partition table until I switched to the new geometry.

Unfortunately there is no reliable method to derive the disk geometry from the partition table. That's why ReactOS cannot detect the old geometry in a reliabe way. And since Windows and Linux do not care about the reported geometry of the harddisk and always use the 63/255 geometry instead, I don't see any reason not to use the new geometry.