That's not the "average home user". The average home user has no clue that they need to do backups. (Hell, the average dedicated server customer I dealt with when I did that support didn't either. "Yes, sir, hard drives are mechanical devices and they do fail, that is why you had the option of purchasing our tape backup services or making arrangements for your own backups")
The average home user doesn't make use of file sharing very often. If they have a network it's to share the internet connection (and maybe a printer) with more than one PC and that's primarily it. For those uses one would be hard pressed to tell the difference between 10mb and 100mb.
