This is not something I personally find use out of, but I know people who would.
People often incorrectly edit third-party themes that have modifications on them.
I am trying to get people to install the third party BUT make all changes to a child theme of that third party product, thus making upgrades easier. If people do not do this but want to, it would be nice if they could take their theme and just edit it so that it is a child of a fresh installation.
What we need:
A plugin that will go through a theme and revert all templates that are exactly the same as the parent. If a theme has a template that has been edited, you need to manually compare and see what the differences are. But if there are no differences but someone pressed the 'save' button, I'd like to revert that template and have a tool that does it manually.
I do not know how difficult it is, but I can pay a little for it. I find it something people can appreciate the use.