As a game master that uses image editing software in midst of the game sessions, I'd like to support this.
Also, I like to use screenshotcaptor (a little free app) for taking partial screenshots of PDF pages and temporarily show them to the players when it's about rules or book contents. Since each screenshot can be just stored to the clipboard (the quickest option), it would be cool to be able to just paste the image from the clipboard to the Roll20 app without taking the extra steps of saving the clipboard content and then seeking the file for dropping it inside the app.