Completely agree, I couldn't use my PC without making backups as it would make me too paranoid. Hard drives will always fail at some point, none of them last forever; often it can be out of the blue without any warning signs - I've had one that slowly gave out and another that suddenly completely let go (made the most awful noise).
A good method I use is the Grandfather-Father-Son method. Keep the last 3 sets of backups and chuck the oldest. If you use rewritable discs (NOT recommended), always backup to the oldest set so that they are cycled.
And of course, great for just restoring individual