Many smaller and/or cheaper computers do not come with a CD/DVD drive.A flash drive is less likely to be physically lost because they cost more than a CD/DVD and more care will be used.A flash drive is less likely to be lost in the growing pile of computer CD’s and DVD’s that you’ve amassed over the years.A flash drive is less likely to be damaged (scratched, broken, etc).
You may be asking why you would want the ability to install Windows 7 from a USB flash drive.
