In the described situations i absolutely do not need a scripted fear effect.
First, those usually are enough to make me concerned about my characters precious life, so running off screaming happens intentianally (if the situation is indeed overwhelmingly dangerous).
Second, the NWN fear effect is crap. Running around like a blind chicken, preferably away from one opponent towards a few others or straight into the next corner where the chasing opponent can beat the frightened, helpless character to pulp. Or usually running towards a passage and then behind it - so if the monster follows, there is definitely no way to escape.
Thanks, of that i do NOT need more.