I've seen people moaning about how Angela White hasn't been getting her kit off in more recent scenes and speculating as to whether it has any deeper meaning. I haven't seen any of her recent material so couldn't really comment; but it is probably all just speculation anyway.
The people who flag these things up obviously just want people to be naked, so get grumpy/confused when/if they don't.
Anyway, this is quite a generalized thread that has been created for something which actually must be said with at least one or two people in mind.
I would imagine whether girls get fully naked or not is a mix of personal choice, either of them or who they are with... and/or the script. Anything else is a bit speculative.
People are always searching for deeper meanings when it is probably just a case of mixing things up or chance. Just because someone doesn't get naked doesn't mean they have something to hide.
e.g. my interpretation of this thread is you like seeing babes get fully naked and want to know why it doesn't happen all the time
Well, I like full nakedness as well but not everyone will and it is everyone's tastes who are being catered for and not just your own and "variety is the spice of life" and all of that stuff. If someone is partially clothed in the same area time and time again in scene after scene then there is likely a good reason for it but even then it might be down the personal choice.
*shrug*
Plenty of porn out there, so just focus on what you do like. Full or partial nudity isn't actually a search filter on most porn sites I don't think, even though it possibly should be.