How important is the oil slinger??..

QuickDart360 said
Not overly important. Could do without it. But better to use if available. I guess you can put back in when the time comes for some repair.

I totally agree with you.
It's intended purpose is to keep oil away from the front seal and is not a big deal if omitted.
The seal technology probably got better in the later years, that's why the factory omitted them.
They probably saved a buck an engine by deleting them, and that adds up!