Saying that she isn't an innocent or naive victim that some are trying to paint her as, and pointing out facts is not the same thing as calling for her to be punished in any way, shape, or form. Nor is calling out the fact that she is bringing a good bit of any current negative publicity on herself. Most of us didn't know anything about Hillary's friend (and comments that were made years, more than a decade in fact, ago) or even the press bringing up Lewinsky, so had she not spoken out here, then it is likely that such things would have died down (as they likely already have) much sooner than they ever will now.
Now, I will say that Beyonce's lyrics are wrong, but it happens. (I've never even heard it but then again I don't frequently listen to Beyonce.)
No one who was old enough to have realized who was President for most of the 90s is going to forget the scandal. But the way to get over it is not to bring it up, even if others are doing so. This isn't fixing anything, despite what she may think. People are not going to change their opinion about her with this "essay", and especially not with a book (if there really is one). It is just going to bring it back up to those who knew but didn't care, or cause those who had very little knowledge about it to actually check it out.
Most of the comments "for" her are just as politically motivated as most of those "against" her or "for" Clinton. The proof of this is found in just looking at some of the very first comments made by news personalities and political pundits when this came out, and tying it to Hillary Clinton's potential candidacy in 2016.