Hey there, Movies4Days!
I have to say that you really got lucky!
Usually if you unplug an external hard drive while still reading the data from it, it may corrupt the drive.
Anytime you interrupt the active read/write process of any drive, whether by pulling the data cable, power connector or NOT safely removing it, there's a chance that both the data and the partition of the drive get damaged. If that happens, it can cause the drive to show up as an unformatted or RAW.
The 'safely remove' is simply a sort of security that is preventing your from destroying your own files.
Hope this answers your question!
Be careful and always keep backups of your data on a different storage device!
SuperSoph_WD