It's not available on some positions because it looks weird or messes up the animation (blowjobs, for instance).
You can always turn on camera look in a position by editing the associated XML file (from the
Sex Sim\Runtime\_aData\animations\info folder), if you really want it on. To do that, open up the XML file for the animation in a text editor and look for the following lines:
<CanLookAt00>1</CanLookAt00>
<CanLookAt01>1</CanLookAt01>
<CanLookAt02>1</CanLookAt02>If any of those is set to 0 then that means the character can't look at the camera. If you set it to 1 and save the file, then they can.
Keep in mind that the animation XML files aren't meant for editing and thus may get written over when updates come out, so you might need to re-edit them later if that happens. But hey, if you want to do it, it's possible already.