Since I don’t keep any images in my desktop or user folders, I just had it scan those folders. Didn’t bother me, it only took two seconds.
Well, not everyone is as lucky as you.
actually really want to find a good facial recognition/tagging solution for my (thousands and thousands of untagged) photos
I think you missed the point. It’s about involuntarily being subjected to it.
That goes far beyond a mild complaint on a bad GUI. Did you miss the part where one has to literally force quit the Picasa app? Or, the part in their EULA where they can very well suck up that data without your knowledge?
For example, the Apple iPhoto app will first ask you where and when to scan folders only when you ask it to and can be canceled before it ever does it. iPhoto only performs facial recognition only when you ask it to and can be canceled before it ever does it. That kind of opt-in approach is not only a much better way to implement a user friendly approach to the interface, but is also a far more ethical approach to user privacy and safety.
Picasa tries to shove Google’s tentacles down your throat. Screw that.