I agree with technologist...
Backing up your data has nothing much to do with a system crashing, it's just an additional security in case of a hardware failure (which can happen to EVERY piece of hardware, including Apple's ;-) ) or a user error. You can't imagine what kind of things some users do, ending up with deleting all their mails, settings, data, etc. and when you (as an administrator) ask what's the last thing they've done, the answer is always "Nothing!!".
To make things short, if you have important data you want/need to keep, you should back up regularly, no matter what kind of computer or OS you use.