Here is a dreadful hack: scaling the image to several times LARGER than its normal size–for example, four times larger. Then crop the image, save, edit the image again and scale it down to one-fourth of its current size. It’s a terrible way to go about it, but it is faster than doing a local edit and re-upload.
Still, changing a WordPress setting to simply allow the user to crop to any size would be much, much better.
