Action items currently have an "owner" field to keep who is responsible for the action item.
This can be a bit confusing as we've had people assume "owner" is the person overseeing the action, or needing the action to be resolved by an assignee. We have literally had people put the person's name of who is doing the task in the "Action Item Name" field. Which of course means they never get done because the person can't see them in their task list.
I'd like to see reuse of the way workflow activities are assigned. Then you could track reassignment of an action item. Use calendars for out of office, etc.
I know this would likely be a somewhat large change to action items, but I feel it would better fit into the Windchill narrative.