Consider adding a third option to copy-paste-protection :
1. everything can be copied
2. nothing can be copied
3. Short text can be copied (e.g. 255 chars)

From a reader perspective, not being able to copy anything from a long document is unnecessarily annoying. E.g. when an author quotes a scientific reference, one cannot select the text to look up the reference. (hyperlinks may be clickable, but not every reference is a hyperlink)

From the author's perspective, I think most wouldn't object to copying short bits of text; what they perhaps want to avoid is readers copying entire pages.

So, why not implement a third option, or a sub-option (preferably the default) to allow copy/pasting of short bits of text even when a document is protected ?

The current total copy-protection is just annoying to most readers, whilst professional plagiarists will find other tools to circumvent them.