One day you found out that your laptop / computer refuse to work and there is nothing you can do about this except to bring it to the store and ask them to fix it. It will take a while and you will stuck since most of your data is in your hardisk and you cannot get it sit the computer is not working.
So, imagine if your computer (laptop / desktop) have allow you to access its hardisk directly. The technology is there, as simple as technology that we have in external hard drive which commonly possess by every one.
The direct connection will allow you (or your IT guy) to save the data without opening your laptop, install the new harddisk image and hit the road with no time..
Imagine that ...