I think securely deleting any sensitive data you may have on your pc is simply good practices. Whether you actually need to, for whatever reason, may be another matter. It's really no different then using complex passwords. Though you may not be in any danger of having someone trying to access your accounts and what not...it's still good practices.
One good argument for routinely erasing your data is you may eventually pass your HD on to someone else. What you had on there, whether sensitive or not, is really no elses business.
:roll: