Please read through this before responding.
I have added a download button in the lightbox for images posted in the critique forums, the important part of this to note is that critique forums are only visible to NPN members, any non-members cannot see the critique forums!
What this does is allows other NPN members to download your image to demonstrate post-processing techniques without having to use workarounds on the right-click limitation. I have also added a note that will go on the end of each post:
You may only download this image to demonstrate post-processing techniques.
In other galleries which are open to the public, the download button is not visible, and right-clicking is not allowed. There are still ridiculously easy ways to circumvent this as with any website, but it makes it slightly harder for John Q. Public to download your images.
I would hope that we have enough trust between fellow members that this download button will be a non-issue.