I don't know any of my female friends that shave down there consistently.

I think in the porn industry it's usually to make them look younger, or it is, in general, more preferred.

I think having them not shaved down there is an attempt at realism.

A bush hides the pussy a bit more. It's convenient censorship, if you will.

Hardcore is made to look good.

So is softcore but they don't show the vagina so if you see it, it's an accident and they haven't made the effort to idealize it.

If you compare Western porn to Japanese porn, you'll probably notice that most JAV models tend to have full bushes, or trim their pubic hair very little. This is also likely due to the fact that Japanese law requires a certain amount of censorship in their porn, and a dark patch of pubic hair makes it a lot easier to hide the genitals in certain shots.

Of course, there's always exceptions. Some Western pornstars are starting to sport full bushes simply to buck the present norm (which hasn't always been the norm, I still remember seeing full bushes in porn well into the 1990s, then in the early 2000s all the pubes seemed to disappear overnight). And in the opposite direction, Japanese porn isn't as strictly censored as it once was, so a lot of modern JAV models are starting to shave off more hair down there as well.