We updated CKEditor to the latest edition at the time of 2.6.0.0's release, and the drag-&-drop plugin that mojo had was no longer supported by CKEditor.
It was a neat feature and that most people didn't use and it kind of encouraged people to dump everything into the media folder, which is very messy and makes managing those files harder down the line, so we decided to not to replace the feature.
I will look into making the workflow of uploading/adding images easier, but for now I'm afraid I don't have a better answer for you.