I think Jeremy hit the nail on the head. I've also commented about this in the past too.
You can chuck awards around at great creative, and BTW I loved the original gorilla ad, but unless it adds to the advertised product's bottom line then it's failed.
The world and its mother knows about CDM and to my memory it's not reinvented itself in a good few years - I still remember being given CDM minis as a treat by my grand father when I was about 4 and I'm now nudging 40! Packaging's the same, product looks the same.
With Galaxy, at least they've gone to the effort of funking up the packaging and nicely texturing the bar in recent years.
I reckon CDM is a "session" chocolate, whereas Galaxy is more of a treat. With health kicks and shrinking disposable income, binging on "bucket loads" of choccy are now out of the window. Could be a reason...