I shoot film, and to digitize it I either shoot it with my DSLR on a lightbox rig that I made, or a flatbed transparency scanner via vuescan. In either case, the image comes in as a raw file of the negative, and while you can pull the left curve points up and the right curve points down to invert the image, then all the controls are backwards, e.g. pulling the highlights out affects the shadows. Can there be a simple check mark to invert the curve? That would be super helpful.
A lot of people still shoot film and are having this issue:
It's not going to get seen here.
Your best bet is to raise an idea here http://feedback.photoshop.com/photoshop_family
Then link to it in the forums, stating your case. If it's popular, it should stand out.