You make a fair point but ...
people add and remove things from their NAS's all the time that just life. If there is a way to stop having to reboot 12 disks then that way should at least be considered to be added.
Also not having any control of the "disk is scanning" thing whilst a PITA for me is a much bigger deal in a company.
Boss says to IT guy... how long will the outage be. ... IT guy says.... well if I reboot it will either be 10 mins or 10 hours. In the real world answers like that don't go down well
But this is linux after all... rebooting to mount a drive is a bit curious IMHO