Although I can't be the only one who puts various cron jobs
under /etc/cron.d that get run at various times.
Almost every administrative cron here is in a cron.d crontab file .. we
need control over exactly what time certain things happen. So please
keep the functionality.
If systemd is the expert spawner - then perhaps things like cron (or
any reproductive daemon for that matter) could lean on a systemd for
spawn service - but leave the other application specific parts to the
local daemons to do for themselves.
There is some merit in functional separation too ...