Don't know why one would actively try to keep it though.
Well from a security design point of view FBE is damn poor, especially if like me you have an unlocked bootloader to allow you to install a third party OS and packages.
One big no nos with FBE is it's up to applications to decide what they want to encrypt, so if I save data vital to me in FBE then the application I'm using decides it's not encrypting, my original reading was even things like WiFi passwords weren't encrypted.
Even encrypted FBE data is vulnerable, say I flashed my device with a new firmware to open this up. Or can get into my phone somehow after boot (adb or a flaw on the OS). This has all happened in the past on different devices and OSs.
With FDE everything is encrypted and I'm not reliant on some nasty encryption enclave chip to give out the key, these have been found to have flaws in the past too.
I have FDE set so my boot password is quite long and my unlock password is shortish. So you can't flash a new firmware to get into my device, everything is encrypted. All my files, irrespective of application are encrypted. This is strong from a security perspective (LUKS is well known technology). The security level is under my control.
FBE is okay with a locked bootloader and you really care about not missing alarms calls, but to be honest how often does your phone crash? FDE used to also make a noise if a password wasn't entered for a long period. FBE is also less hassle for users as no complex password to enter at boot.
Happy to be corrected on FBE.
But to be honest the only people that probably should be happy about FBE are government agencies. Much easier to get data from a device that always boots up than one stuck at a LUKS password prompt.