So I'm taking it that the average Country music fans weren't impressed by the vocal (and other) delivery. It did seem to fit urban more than country.
I don't think you can make that assumption. Popular culture isn't always based on vocal delivery. There are lots of other factors. Looking at social media, I saw a lot of comments from people who saw Beyonce as kind of a country carpetbagger, without any real desire to reach out to country fans.