I can't speak for other customers, but since 99% of our content is plain text, why not make it so that content pasted into a story asset is -- by default -- plain text?
Then, instead of having a "plain text" button, have a button to retain formatting. Reporters and editors often forget to use this button, which causes code to be hidden in copy until it's ready and on the page, where it can be dozens of characters. That would eliminate this issue.
Customer support service by UserEcho