I can see a certain logic to holding Buick.
In China, Buick apparently is doing very well. It used to be the Emperor's car or some such thing. If GM really wants to continue to compete there (and it may soon become a fool's errand), they probably need to keep Buick. That doesn't mean it's needed in the US, but they'd have to finesse that somehow as at least some of the Buicks are exported from the US to China.
I don't disagree with you on the rest. GM has killed the value in most of their brands, so getting rid of the names wouldn't be that much of a loss. There's no reason why a Chevy dealer couldn't sell a G8 or an Aura or an ... They could keep Cadillac separate as a premium brand (there's a certain logic in that), but they don't need 2-3 entry brands and 2-3 mid-range brands and a near-luxury brand in the US.
Saturn was Roger Smith's pet project and never had a chance. The rest of GM wasn't capable of learning the good lessons from them (if there were any), and their cars were never good enough to be world-beaters.
Also, once they started putting Chevy V8 engines in Oldsmobiles the management at GM should have realized (yet again) that there were far too many brands and too little to distinguish the cars. They could have made GM much more efficient starting in the 1970s for crying out loud. Trying to do it in a rush now will mean a lot of pain...
GM has 12 worldwide automotive brands (excluding Olds).
http://www.gm.com/utilities/gmsites/
Toyota has 4 worldwide brands.
http://www.toyota.co...x_automotive.html
That should have told GM management something a long time ago. Trouble is, all of the VPs and GMs of the divisions that would have gotten the ax probably weren't too keen on giving up their very well paying jobs for the benefit of the company (and the country). It's not surprising that little changed. :-(
Cheers,
Scott.