I'm pretty sure most people would prefer to be able to recover their DNS in case of catastrophic failure over 100% cryptographic security. The technical aspects of security are never the whole picture.
Or to put it another way: Not being able to recover access is not something most people will accept and if your technical security measures don't consider that they will be worked around. If people need to go through support to recover their DNS more often then support will be used to giving out access to people's account and that will also reduce YOUR actual security.