Doing this by default would be nice, or at least giving an option. I was able to get it working myself after wrestling with screenshot.sh and digging through settings files to find out why it was saving instant screenshots as jpeg by default. wl-copy only puts png images on the clipboard so with the default jpg extension and filetype it wasn't working.

Would be nice for people who want the functionality but don't want to/are unable to modify scripts to accomplish it.