Thunderbolt connectors need to be in close physical proximity due to the very high speed board layout requirements. Sonnet thought it important to put the connectors outside to give rear panel access to connect additional Thunderbolt devices.
Sonnet wanted to support both deep server room racks as well as shallow portable racks (the xMac mini server is only 18" deep.) Because we couldn't accomodate the full range of rack depths, we unbundled the rack kits to give the users the flexibility to mount the xMac mini Server in racks 18" to 32.5" deep.
