I believe it has more to do with numbers being used so frequently in our society that they can help to create a sense of eerie coincidence. If you're FBI, you feel extra alert round about Hitler's birthday, because these guys like to try to make shit happen round about then.
This is the sort of numerology that reminds me of "Jonathan Doe" in "Seven," who specifically wants to leave behind some statement about sin. However, Doe must be about a zillion times smarter than these guys.
The "88" code has been in use for many years, but going for 88 sounds more like braggadocio than anything else.
As for fourteen, let me try something: "We must secure the future existence of white people and our children." Let's see, I think that pretty well covers everything and is only twelve words. You would think they wouldn't need those last two killings just because they're redundant.
