You are linking things that do not need to be linked Telkar.
PfA is a strong spell, with a limitation that it protects against a chosen alignment and is a proactive measure and has no reactive utility.
I am talking about DnD, not about NWN or about PotM. The spell is not anymore powerful than it was designed to be with the exception of a longer duration and the fact that NWN treats fear auras as mind affects. The thing that gives people a misconception about the spell is that in PvM especially in a Ravenloft setting, the utility of the spell is increased by the near unanimous nature of all enemies falling under one alignment.
That's the spell, its not overly powerful, its that its limitations do not come to pass as often as intended in this environment.
It has nothing to do with Mindblank. Mindblank is a mage spell, it is not on the Cleric,Bard or Paladin spell lists. It is a superior spell to PfA in every way except duration. If Mindblank was the level 1 spell it would truly be broken. The fact that neutral aligned spells are covered by Mindblank is a strength of the spell, not a limitation. It is actually a spell that makes Wizards more valuable to a party at the high levels. In every way I prefer a Sorcerer in a party at higher levels, but a Wizard has more specialized spells such as Mindblank.
My opinion is that neither spell needs to be changed. Perhaps decreasing PfA to turns/ level is the best one. It would change the dynamics between the spells that protect against mind affecting spells. Increasing instances of Neutral spellcasters would increase instances where the limitations of PfA come to pass. Its the lack of PfAs limitations being exploited much more than any problem with Mindblank that has fed the misconceptions.