I think there is quite a difference, as those (however sarcastic) would destroy a job(or tactic for that matter) and this would simply limit a job. I admited it's probably impossible to cleanly make a change like this now the game is so far in, but it is something SE probably should of done in the first six months of NIN's release.
To explain the difference...
Let's make it so when you use a weapon skill mobs retaliate with death that goes through shadows. That'll teach those melee burns.
This would prevent players from using weaponskills.
Having single-target magic go through, ignore, or wipe shadows(without damage).
This would prevent players from ignoring monster spells with incredible ease in almost all situations.
While I know you are being sarcastic in your examples, however a nerf like this isn't nearly as bad as let's say the Ranger nerf. NIN and /NIN will remain by far the best way to ignore physical damage. A NIN could get a Elemental or Magic Resistance build and be fine, abit weaker than before, but even Rukenshin said it himself that it feels almost unfair the way he is able to reach amazing amounts of magic and physical resistance gear while only getting hit by something 1/20th of the time.