Miranda's fans have the same complaints we have about lack of promo, airplay, and single choices. I think Kellie's songs are more mainstream and radio friendly. Just 1 example, I'm guessing Small Town Girl would score a lot higher than Famous in a Small Town did on Hit Predictor, and Small Town Girl deserves to make top 5. It would be interesting to compare the scores of all of their singles. It seems that Sony BMG and radio stop promoting both Kellie's and Miranda's singles when they reach around #13.
To me, the fact that Kellie's album was certified and sold gold at retail so much sooner than Miranda's 1st (about 10 weeks vs. 9 months) just further confirms that Kellie's album should have gone and sold platinum by the end of 2007, not 2 years, if it were not underpromoted and undershipped. I don't think Kerosene has sold 1,000,000 at retail yet although I'm not sure.
Provided they get decent airtime I believe music videos help single, album and concert ticket sales and possibly help airplay (maybe some program directors take songs released with videos more seriously, I don't know). Plus videos keep fans excited, interested and voting for them. If music videos didn't help, why would anyone bother to make them? Taylor has a video for everything and I can tell her newest video was made to promote sales of the deluxe edition CD/DVD. CMT offers the album for sale on the video page
CMT : Videos : Taylor Swift : I'm Only Me When I'm with You