Sometimes when you are adjusting plugin parameters you realize you want to undo all the changes you did since you last saved the project. The undo history is not specific to the plugin settings so that is not very useful to revert just the settings of the plugin. You can save a preset by name but that has to be done manually and it is not project-specific.
It would be very useful to add a "Revert to last saved version" action to the FX preset list -next to the reset to default action- to reload the plugin parameter settings from the one in the last saved version of the project.