In my (admittedly limited) experience, schools only care about the rankings because they know the general public believes they mean something. No one I've encountered in academic circles actually takes them seriously. What US News doesn't want people to know is that they send out these questionnaires out to the top administrators at the various nursing, law, medicine, etc., programs and ask them to respond. However, because most of those individuals feel they have little first-hand knowledge or experience of other schools and are understandably reluctant to get involved in passing on vague generalizations, most of the people polled don't respond. US News ends up doing the rankings based on the objective info that is publicly available, like the amount of government research funding a school gets, how competitive the school is (# of applicants vs. number of accepted students), etc. Most of which has little or nothing to do with the quality of the teaching, experience/expertise of faculty in the different specialities, and other things that would actually have relevance for potential students.
At least, that's what experienced academics have explained to me in the past when I've asked.
However, I am certainly not suggesting that the general reputation of a school and reputation of a nursing program, specifically, doesn't matter. I'm just saying that there are serious limitations to the USN&WR rankings.