Like Facebook, there can be a feature of deactivation of an SE profile, where the account is not deleted permanently but deactivated until next login for activation. All the user data is restored once the account is reactivated.
I support it.
One strong use case is that an "Inactive user" will not cause reputation loss to anyone. It happened recently in our site to several users.
Additionally the username while deactivating may remain as it is, if the user chooses to. However this username will not link to any profile due to deactivation.
Upon reactivation, everything would be restored like before.
Deactivating my account