I've suddenly realised what Microsoft is talking about! We've been looking at it from the wrong side.
The UAC is not there to help keep users secure. If you think about it, it is there to allow developers to keep writing the same security-busting code they have done since Windows95.
Take a leaf out of Apple's play-book. If you don't keep your code up to date, then you don't get to play.
***DING*** ***DING*** Give the man a ceegar.
UAC has never been a security feature. Microsoft has NEVER claimed that UAC was a security feature. It's a convenience feature that acts as a forcing function to convince software developers to get their act together.
And if you don't like the default settings, you can make a trivial change to increase your prompting level back to where it was in Vista and all these "exploits" go away.
The ONLY secure scenario is to run as a standard user (with no admin privileges) and use fast user switching to switch to an admin account when you need to make configuration changes to the machine. But most users won't put up with that level of security.
Heck, look at how much people complained about the UAC prompts. Imagine how annoyed they'd be if MSFT forced them to log into another account to change their system configuration.