I'm not sure if I took this for granted or if it's mentioned somewhere (I'll try looking it up when I can), but I always thought Broodmothers were more-or-less subdued until a Blight, and then would become active when there was one.
Incidently I hated that part in Origins; listening to the female dwarf talk about how they made Broodmothers in that dead voice. ;_; All the chills were felt that day. Some playthroughs I'd turn subtitles off and volume down to avoid hearing it. >_<
I seriously space barred through her poem EVERY TIME after that.
No one wants to be confronted with forced cannibalism, rape, mutation, and batch-pregnancy. NO ONE.
Especially when you're playing a female warden whose fate is to go down to the Deep Roads alone once the Calling hits a fever pitch. Seriously. Men probably get to die all nice and noble, while you're carried off into some forgotten thaig and turned against your will into a monster whose sole purpose is to spawn the very thing you've fought your whole life against and defiled you.
BRB, need to go vomit somewhere.
I guess I'm really twisted then, because I loved that part of the game. Not because I actually love terrible things happening to innocent people (in real life just the thought makes me so sick I shake uncontrollably, vomit, and pass out) but because, in the safety of a fictional setting, I thrive on the drama derived from the horrific and macabre. I love hearing Hespith's ironic nursery rhyme because it makes me ill, both morally and physically.
It definitely does add a layer of horror for female Grey Wardens who are expected to face the Calling. It also explains Alistair's observation that there have never been many women in the Grey Wardens (although BioWare seems to have ret-conned that as of Inquisition, because it seems to me there's roughly an equal number of female Grey Wardens to male).
Although, one must note that the darkspawn want fertile women to serve them, and Grey Warden women are practically sterile thanks to the taint. It's possible the darkspawn sense this (since Wardens and darkspawn can sense each other, especially Wardens so far gone they hear the same music as darkspawn) and so don't want them for Broodmothers. In fact, I'm almost sure I read a quote somewhere (but can't find it now) where an angry fan called Gaider out on putting Grey Warden women in the position to get turned into Broodmothers, and he calmly responded that Grey Warden women have limited reproductive abilities. I can't remember exactly what he said, but he basically implied that they're safe in that area thanks to the side effect of the Joining limiting their fertility.