I would not take the lack of female influences too seriously. First, little boys (judging from the names, most of the respondents are male) tend to focus on male singers when they are very small. Second, at least in my opinion, the great female singers tended to be more "followers" than "leaders" when it came to making a new sound or breaking any kind of mold. This may have been more a result of the control of the producers of the day dictating their content rather than the women themselves being "followers." But, having said that, if I had been a little girl and could have anticipated singing soprano or alto, here are some great female singers who have been very influential to the modern scene:
Tammy Wynette, Patsy Cline, Loretta Lynn, Dolly Parton, Emmylou Harris, Lynn Anderson, Anne Murray and of more recent vintage, Allison Krauss (please forgive if I misspelled any names!)
I cannot hear Leann Rimes without being transported back to some of these legends of my distant past. All these singers have songs that touched me deeply, but in terms of aspiring to sing like them or follow a style that they pioneered, I'm afraid my gender kind of stopped that. In one sense they all share one feature that I do hope to follow, and that is they all sing clearly and strongly and with a great deal of emotion. These women were, and are, tremendous influences in country music, at the very least.