So... aren't these mostly DLC tracks? Isn't this just another way of distributing their regular stuff to people who don't have an internet connection?
This just looks to me like RB opening up their game to a wider audience, and finding sales venues other than DLC. There probably is not a lot of crossover between the buyers of this Country Pack, when referenced against Classic Rock Pack or AC/DC Live. And in those latter cases (and probably all cases) the songs can be exported to the main games RB1 and RB2.
GH on the other hand is releasing Aerosmith, Metallica, Van Halen... those are standalone, not available as DLC, and not exportable to GH:WT, right?