I don't think the vast majority of women who do that are doing it intentionally. Some do, obviously, for effect, but I think it's actually just a natural resting place for lot of women's voices. It's one of those things that once you learn about it, you hear it everywhere, but something you never noticed until someone points it out.
It appears to be far more common in women than men. But I think there is a measure of sexism when it comes to "vocal fry" because nobody ever complains when men talk that way (in fact they tend to get complimented on their "sexy" voices when they do that - Bradley Cooper talks that way all the time) but when women do it, they are scorned for it.
At any rate I would expect someone casting a commercial to disqualify an actor who did that, but I guess that just shows a lot of people aren't aware of it, and don't notice it, until someone points it out to them.