The reason why I would prefer to have systemd respect the "debug" flag, even if it means that kernel developers have to learn a new workflow, is that there are a lot more system administrators than kernel developers out there, and (on average) the kernel hackers have lots more expertise than the admins.
By this logic, there are a lot more servers than there are desktop Linux users, and more than likely a lot more system administrators than desktop Linux users (I believe I'm in the minority as I'm a system admin, who uses Linux daily on all his computers, desktops, laptops, and servers), so the things systemd does that are intended to make the desktop linux experience better, like faster boot (which was never strictly a problem on servers, except in the time it usually takes a server BIOS to get to the grub prompt, which systemd can't address), "better" hot-plugging of devices, socket activation (which already had a solution and is something you don't want on a server for the example use-case of mysql), the FSS logging that journald does (because sysadmins have already sufficiently solved that at scale) so systemd shouldn't be encroaching on server linux use. And there are a lot more system administrators out there than desktop environment developers, and (on average) have more system administration experience than the desktop environment developers.
This also assumes that sysadmins don't use the kernel debug flag, and only kernel developers do. I've had to use it on the rare occasion, and I've been glad that messages from the kernel are easily selectable via a specific kernel command line option as distinct from userspace messages.
By this logic, there are a lot more servers than there are desktop Linux users, and more than likely a lot more system administrators than desktop Linux users (I believe I'm in the minority as I'm a system admin, who uses Linux daily on all his computers, desktops, laptops, and servers), so the things systemd does that are intended to make the desktop linux experience better, like faster boot (which was never strictly a problem on servers, except in the time it usually takes a server BIOS to get to the grub prompt, which systemd can't address), "better" hot-plugging of devices, socket activation (which already had a solution and is something you don't want on a server for the example use-case of mysql), the FSS logging that journald does (because sysadmins have already sufficiently solved that at scale) so systemd shouldn't be encroaching on server linux use. And there are a lot more system administrators out there than desktop environment developers, and (on average) have more system administration experience than the desktop environment developers.
This also assumes that sysadmins don't use the kernel debug flag, and only kernel developers do. I've had to use it on the rare occasion, and I've been glad that messages from the kernel are easily selectable via a specific kernel command line option as distinct from userspace messages.