Hello Parnassus,
The simple answer is "because we can and I didn't think it mattered." We can always change it back on the fly if we need to anyway.
The longer answer is because of old legacy pre-defined Cisco VLAN's in the low 1000-range. When we re-build our VLAN scheme 10 years ago we "reserved" the whole 1000-1099 range for specials like these, thus is not part of our VLAN scheme thus it matters not for us if I use 1000-1053 or 1000-1099 for the internal-VLAN reservation on the Aruba 8320 as we will never use those VLAN's ever on our network.
According to the documentation:
Configures the VLAN range reserved for internal use for route-only ports and LAGs. The internal VLAN range cannot include any VLANs that are already in use. If the number of internal VLANs is less than the number of route-only ports and LAGs, some ports will be blocked and unable to be used. When the internal VLAN range is modified, traffic on route-only ports and LAGs is briefly interrupted while they are moved to the new range. The no' form of this command sets the range to the default of 4041 to 4094.
The upgrade went fine as far as I can tell. I used a command-line download via TFTP then rebooted the switch manually. After 10 or so minutes it was back. We only use stand alone Aruba 8320's.