Imagine trying to get new, young developers to adopt C or Pascal when the likes of Rust and Python exist. You can make arguments for a thing's superiority based on moral standards (which are always subjective), but morality is a poor metric. If everything was done based on that, the Linux ecosystem would be in the same state as the GNU Hurd kernel.
The choice of init system is up to the distro maintainers because init scripts are usually created and maintained by the packager of a given application. Debian for example chose its init system via a democratic vote. Distros that focus on different init systems exist, like the Debian fork Devuan.