That's why I think the default should always be "babysitter mode". Unless you give a specific set of commands, the GPU does what it does and the display does its thing.
Regarding people who turn on "expert mode" even when they don't know what they're doing, that doesn't seem to be a good reason for not having it. The Mark Twain quote about censorship being like "telling a grown man he can't have a steak because a baby can't chew it" comes to mind.
Let's say a hardware manufacturer writes a firmware that exposes calls that can degrade or destroy the device if misused, and the OS driver in turn exposes those calls to third party programs.
If a program wreaks the device, who is the end user going to blame -- the program, the driver, the manufacturer, or all three?
Apple attempt to do this sort of "approval" the with apps on the app store and there have been lots of examples of apps which break the rules getting approved (and then being pulled when they got popular). What makes you think graphics card manufacturers would be able to do that with games?
You also have the problem of people choosing to use "expert mode" because it's faster, obviously.