Because PySDM, mountmanager, disk manager, whatever else is out there left the building before the memo got out about using UUID's instead of /dev/sdxy.
From then on my memories are a bit foggy but I think I remember wondering why was PYDSM displaying my original NTFS partition as sdb instead of usual sda.
I would suggest using templates instead. For ntfs:
UUID=DA9056C19056A3B3 /media/WinD ntfs defaults,nls=utf8,umask=000,uid=1000,windows_names 0 0
** To find the correct UUID for your partitions:
UUID=076426af-cbc5-4966-8cd4-af0f5c879646 /media/Data ext4 defaults,noatime 0 2
** You will have to create the mount point yourself, for example:
sudo blkid -c /dev/null
** Then add the template with the correct UUID and mount point to fstab:
sudo mkdir /media/WinD
** And when you are done editing fstab and saving it run the following command to test for errors and mount the partitions without requiring a reboot. You will know before you reboot if something is amiss. :
gksu gedit /etc/fstab
If there are no errors it just comes back to the prompt.
It's a lot easier and as you have found out a lot safer to do it this way and you don't end up cluttering fstab with a lot of useless ( user ) or absurd ( users ) mount options in fstab.
But this is just my opinion