I like immutable distros. What i do not like is that developers and maintainers do not give possibilities to admins and powerusers to build a immutable core themselves. This removes choice and learning experiences for the customer/user/admin.
For CoreOS, you can create immutable images as easily as you can create Docker containers: https://coreos.github.io/rpm-ostree/container/
You can later just point the installer to your OCI image and it will just work
Maybe this will finally change.