In HSMWorks, you can drag and drop a tool from one operation to another, and have the toolpath updated to use the new tool. It's incredibly handy, and it's absence in Fusion made re-assigning and cleaning up my tool library fairly painful.
I'd love to see this added to fusion, and think users would greatly appreciate it.
In addition, a thing that isn't possible in either, but i'd love to see.. The Tool Library does a great job of presenting an overview of tools and the operations which use them. It'd be awesome if we could drag and drop operations within that UI to reassign the tool being used.