why is add the extra restriction of the partition size?

Because during initial tests we found some disks do not specify a serial number correctly, so we had to do that.

I would appreciate a way to manually change it as a temporary fix.

unfortunately this is not a small change, though it may look so; it is a lot of work, as it requires to update all the stored procedures and will require a database upgrade. So we won’t be able to do this soon. We have more urgent updates to make first. I will try to stick in the next bugfix release, but I can’t guarantee.