Updates and fixes are desirable most of the time (specially as final user). However, in my experience when building custom images and adding custom changes, not controlling if/when the latest patch is applied can be undesirable, e.g. when validating your own changes. So, I'd say this type of feature would help determinism and reliability for users customizing images.
Finally, when a new version of the system does not work as intended, is cool being able to build a previous version and continue working on some other features/modifications.
Thanks anyway, I am aware of the effort put in Armbian, being as is very useful for people like me.