Your wish is our command. This was actually added in V8, but we don't over-write older Instrument Groups you already set. We added a "BLANK" group, that you can choose when you are on a Plate and it will remain sticky next time to go to "Plates" mode.
You can get the default Instruments by going to Menu -> Setup -> Instrument Layouts and then choose Reset Defaults. You will loose any of your customer instruments settings, but you'd get the new Blank option. You can also create a Blank group and choose it when on a plate and it will be the group that comes up the next time you view a plate.
Also, in the next Version 9, we added a new "Button Fading" setting. This fourth setting will fade the buttons 100%, whereas the current Full is not completely faded. I think you will all love the new Version 9 when it comes out.