I'd be arguing much more fiercely for the nerfing of PfA, if it weren't for how utterly broken Fear is.
Immunity to mind-affecting kills the entire enchantment school. And is accessible for every class, from pretty much level 5 onwards if they so desire it.
Sadly, it makes you immune to fear, and fear is broken, with the fair point that it dosen't so much make you afraid as give you the mentality of a headless chicken, running in random directions then getting stuck, then dying.
What are the views of the anti-nerfers that PfA only protect from Fear, rather than from every mind-affecting spell? That would retain it's use against things like mummies and make people need to face Fear less, without shutting down Enchantment so much.
Then you get Mind Blank having more use, along with Clarity and such, since they'll save you from Hold and Dominate spells, just like you'd need Death Ward for death spells. I mean come on, immunity to fear, and universal saves bonus, for hour/level, against all evil things (see, everything in Ravenloft), for a level 1 spell slot? That's still a good deal right there.