Well, utee's comments above mirror mine (not for the first time). We have a playoff, so the rankings strike me as a bit odd.
Other than the observation you've made many times, that people just like to rank things in lists and they'll do it for almost anything...
The main benefit to the rankings for me, as a college baseball fan, is to see how the national folks view the top teams versus one another, which gives at least SOME indication of where each team might ultimately be selected and seeded by the NCAA tournament selection committee.
It's not 100% aligned of course, but in general the #1 team is going to host a regional and likely host a super, while the #25 team is unlikely to be hosting either.
Well, except if Texas is 25. We often get a regional even if we haven't earned one. Helmetosity, baseball style.