I don't understand why anyone would use passwordless disk encryption. It just seems inherently vulnerable, especially with the threat model of physical compromise.
Entering a password on boot isn't even that much work
replies(19):
Consciously encrypting with a password implies an understanding of the risk of permanent loss. Leaving it unencrypted implies an understanding of the risk of disclosure. Having your drive silently encrypted feels like the worst of both worlds. "I never encrypted or locked it, what do you mean my data is encrypted and gone forever!?"