I would really like to see ZFS make it into the regular install image. Debian already releases an install image with non-free firmware and ZFS is free software

I would really like to see ZFS make it into the regular install image. Debian already releases an install image with non-free firmware and ZFS is free software. It just has an incompatible license. The specific issue you mention about creating the initramfs file is actually not necessary in Stretch since this file already exists. There have been other, more significant changes in Stretch as well. (Note: I've contributed to the Debian Jessie ZFS on Root Howto and have followed this guide for numerous systems on both Jessie and Stretch). 1) ZFS has made it into Debian Stretch, so it is no longer necessary to add the backports repository. You just need contrib. 2) The grub-pc package in Stretch provides ZFS support. In contrast, Jessie required installing the package from Testing, and this could cause issues with prior versions of the Howto, as it would often pull Grub's dependencies from Testing as well, blocking installation of among other things, Gnome. The Howto now ensures that dependencies are satisfied from Stable. 3) Since ZFS and grub-pc can be installed from Stable, there's no need to add the /etc/apt/preferences file for pinning priority.