I am sure that the requests to add more parameters and options to actions (Such as relative changes) will flood in as users conceptualise what they may do with them.
However, one of the greatest limitations of the system is that there are currently only two ways to recall an action – navigate to surface > Control > Actions and press recall or assign the action to a soft key.
I would suggest that adding an option to recall an action, or multiple actions, with a scene recall would be a great place to start.
Ultimately, actions become a more efficient way of completing specific tasks that would otherwise be more convoluted when using scenes, scene filtering, and global safes.
Therefore adding the option to ’embed’ action recalls with scenes would also allow actions to nicely complement the scene system.