Mamagement has 99 problems. Holding a status quo is about minimizing the backlog more than hating change as such.

Even when we can show am improvement in security and usability, and lower training cost because of consistency, it's still another mouth to feed.

If it provides sufficient benefits (which systemd does), it is a no brainer.

As a technical matter, sure.

As a business/ management matter, we frequently cannot do the technically obvious thing due to other constraints.

I would agree, but systemd has been around quite some time now. At this point it is technical debt not upgrading to it, unless you use something better.