I understand your feelings. Country music is hated in the LA area. I am sure that is what prompted the Disney execs to change the music format in the Vacation version. But I think it is a mistake to count Country music out or pinpoint it as the problem in the show. I believe that the show failed because it was always the same show, not the music choice. Country music is the most popular music format in the nation. To have the bears do other types of music, would not fix the problem. Country music, at least the type in the show, invited the audience to stomp their feet and clap their hands. It was a participatory show. Many music formats don't lend themselves to allowing the audience to just let go and do funny things.
I really believe that Country music, with its own quirks and uniqueness, it the best way to go for the show.