This isn't a bad point. It's also worth noting that as a whole android hasn't been the most secure, and fde only works while the phone is off or storage is unm

This isn't a bad point. It's also worth noting that as a whole android hasn't been the most secure, and fde only works while the phone is off or storage is unmounted which may be important for some but most average users don't really ever turn the devices off. So if you're running fde and you get a stage fright driveby, it's fornaught. Making a device more secure when it's off has marginal utility to most customers that aren't on hacker news. And those customers probably don't outweigh the support issues associated with FDE for everyone.