It's about choice and control over your data - an educated user knows that with hardware encryption, it is very difficult to retrieve data if the hardware fails. There's also the trust factor where you would prefer to have the keys, rather than trust some device.

(E.g. Some Western Digital drives have problems with their hardware encryption and made the data on it irretrievable for many - https://github.com/andlabs/reallymine/issues/53 . More here - https://carltonbale.com/western-digital-mybook-drive-lock-en...).

What is being questioned and criticized is the removal of this choice. Especially when a product claims a commitment to privacy.