I'm really not sure why anyone would use RAID 0 as a storage solution. There is really not a worse way to store data.
Pretty sure whomever was working on your computer had also never seen this and so it was logical to install Windows on the RAID 0 array since RAID 0 is for speed.
If you have a hard drive go bad or something like this happens then you see why RAID 0 is a bad idea for storage. You lose your data and no you can't get it back.
The logical way to use RAID 0 is for installing Windows and programs on and then you would have another drive for storage of things you can not afford to lose.
You should be using RAID 1 if you wanted to use RAID for storage.