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
Full disk encryption is just inherently a flawed approach compared to per file encryption. Androids approach of only protecting user data with behind the password and otherwise using a separate encryption key to allow the os to boot to the lock screen and some apps to run (eg alarms) is a more user friendly approach. Unfortunately we don't seem to have that sortve option available to us with desktop OS.